What about proper tire inflation?

Sent by Neil Blanchard | 2:13 PM ET | 05-24-2007

I've driven a Civic hybrid and now drive a Prius. Both give instant feedback on mileage, which really helps. Also, why is the tax credit for hybrids being phased out when we need cars with better mileage? Doesn't make sense.

Sent by Chris Groner | 2:15 PM ET | 05-24-2007

Another major gas saver is to buy a good digital tire pressure gauge and keep your tires set to the correct (or slightly higher) pressure. Keep track of the tire wear (edge vs. center) and adjust the pressure accordingly. Car manufacturers often recommend a lower pressure to improve the ride. This results in more rolling resistance and lowwer gas mileage.

Sent by Tom Mehrens | 2:21 PM ET | 05-24-2007

Inflating your tires to a higher (but safe) pressure can help a LOT.

low rolling resistance tires
(as used on hybrids) can make a big difference.

Sent by Julian Elischer | 2:23 PM ET | 05-24-2007

I have tried having a clean car before a long trip. This seems to help in heavily bug infested areas.

Sent by TyKona | 2:23 PM ET | 05-24-2007

In case anyone was listening and was interested in the idea of joining with others to try to lower our gas bills (and environmental impact), the Arkansas project mentioned in the show is 20 Days in August and can be found at 20days.org.

We're trying to change the way we think about driving, and it helps not doing it alone. What better way to spend less on gas than by using less gas?

Sent by Eric Braden | 2:24 PM ET | 05-24-2007

I have trouble believing that using cruise control will improve my fuel efficiency. When I use cruise the engine pulls and the rpms ramp way up going up even a moderate hill--and there are lots of those here in Iowa.

I'm going to continue driving without the cruise. I don't have any trouble keeping to the speed I want and keeping the rpms down.

Sent by Andrea | 2:24 PM ET | 05-24-2007

What do you think about the hypermilers methods?
Oh btw you can inflate tires higher psithan recommended by car maker but still in the safe range for the tire maker.

Sent by Elmer Costabile, Roselle | 2:25 PM ET | 05-24-2007

You would do your listening audience a great service by revealing the electric vehicle developed by GM in the mid-1990's, and why it is not available today.

Sent by James A Kieffer | 2:28 PM ET | 05-24-2007

Regarding gas prices and saving money I am appalled at the behaviour of people when it comes to speed. When prices started going up it was said that people would react when the priced reached
$ 3.00. We are past that figure and people's behaviour has not changed. In fact the majority will not change.. We are not talking about one's pocket we are talking about saving fuel all around and the overall cosumption of oil. I think people are not responsible and need something above them to make them change a behaviour that is harmful for them (money, cost) and the world ( availability of oil).
There are a number of tactics for saving gas when driving but people again do not bother implementing them. I do everything that I know off and that I hear (like now from the show) and my gas mileage is much better that most people.
Margarita Cordoba

Sent by Margarita Cordoba | 2:30 PM ET | 05-24-2007

I have a Pontiac Vibe that gets 35+ mpg--I drive the speed limit and make sure I keep the tires inflated! No one ever mentions these cars as having great gas mileage.

Sent by J | 2:30 PM ET | 05-24-2007

what about deisel- I drive a 2002 VW TDI and average 44 mpg with mostly around town. on the highway I get 50 going 65-70. this beats the hyrids. Deisel is the same price as regular

Sent by Eric | 2:31 PM ET | 05-24-2007

I can tell you why cruise control saves gas. Try this experiment next time you are on a long drive. Follow a vehicle that has set its cruise control, you can tell this because they are traveling at an exact speed. Try to keep the same following distance, it is almost impossible. You will find you are always adjusting the speed. This means you are wasting the cars energy thru braking (loosing energy) and accelerating (wasting energy).

Sent by Michael Burke | 2:38 PM ET | 05-24-2007

People should empty their trunks and reduce the weight in their cars. Also, I have seen stories that people's increased weights has reduced mileage in cars.

Sent by Ed Andrews | 2:38 PM ET | 05-24-2007

If we are not supposed to drive around town with the air conditioning on (more gas usage) but where not supposed to ride around with the windows down (more drag), how do we keep cool?

Sent by carter | 2:39 PM ET | 05-24-2007

From Car Talk in 1997 - Wind tunnel tests show trucks do better with the tailgate up:

http://www.cartalk.com/content/columns/Archive/1997/October/05.html

Sent by David Royster | 2:40 PM ET | 05-24-2007

Regarding the issue of tailgates and pickups - Mythbusters did a segment on this and determined that driving with the tailgate up is actually more efficient because the air circulating in the bed area deflects more of the oncoming air making the drag less and increasing fuel economy.

Sent by Donal Kennedy | 2:40 PM ET | 05-24-2007

Another good tip: If you're stopped at a traffic light more than 30 seconds, it's more efficient to turn off your ignition and restart it.

Here's one I'd like ideas on: On a tip, I recently started shifting into neutral when coasting, either at speed when downhill or decelerating going uphill. I could've sworn my fuel efficiency went up about 5 or so miles per gallon, most notably when traveling in hilly areas. Then someone else told me that shifting into neutral doesn't actually do anything for rpms, but rather it just disengages the engine shaft. What's the deal?

Sent by Jacob in Baltimore | 2:41 PM ET | 05-24-2007

MythBusters did a piece on the truck tailgate up or down dilema. They determined through scale model and real-world tests that you should leave you tailgate up. The tailgate creates a pocket of air in the bed that reduces overall drag of the vehicle.

Sent by Brian K | 2:41 PM ET | 05-24-2007

I'm stuck. I'd love to buy a hybrid. But I'm bored to tears by driving automatics -- they can have my stick shifter when they pry it.... So, are they making / going to make a manual transmission hybrid? Or, alternatively, are there high-mileage non-hybrid sticks?

Sent by David Gregg | 2:41 PM ET | 05-24-2007

Engine Thermostat: One item often overlooked on vehicle maintenance is the engine cooling system thermostat. For best gas mileage you want the engine to run as hot as possible, as it was originally designed. Replacing a tired cooling system thermostat can raise engine operating temperature, provide better gas mileage, quicken warm up times and improve heater operation.

Sent by Scott at SJMAutotechnik.com | 2:42 PM ET | 05-24-2007

hello everyone....anybody every use a water-injection system on their vehicle?
I have heard gas saving of 10% to 15%. Is any of this true? Thank you.

Sent by Mike | 2:42 PM ET | 05-24-2007

HI
Thanks for your show. I moved from Massachusetts to Vienna, Austria in September 2006. The most wonderful thing here is that we don't need a car because the public transportation is excellent. I hear that trolley cars are catching on the in US.
Now that is good mileage!
thanks again

Sent by Marianne Sutton | 2:42 PM ET | 05-24-2007

I coast (stick shift) if the light ahead is red. Also coast when speed is slightly above the limit and only use gas when speed drops below the limit by 5mph. I think I get about 2mpg more.

Sent by 'Ron Vargason | 2:43 PM ET | 05-24-2007

I have a manual transmission which has eliminated brake pad changes for the 85K miles so far on my car. Manuals allow for much less braking. For example, foot on the brake at a light is not necessary. Been driving a manual for 35 years.

Sent by Linda H. Latimer | 2:43 PM ET | 05-24-2007

I think they mentioned it in the intro but haven't talked about it yet is coasting down hills. Is it more effective to stay in gear or shift into neutral?

Sent by Karl | 2:43 PM ET | 05-24-2007

Driving safely is good, but restricting driving can crimp productivity. Cruise control can also be dangerous in situations that require quick reactions. As a previous guest who supported health insurance companies explained: Americans want it all! We want the best. We want to be able to drive -- for business, for pleasure. The first cars were electric (see the documentary "Who Killed the Electric Car?"). Let's advocate making electric cars available instead of fighting over oil. That is a convenient and safe solution that maintains our freedom to drive. Freedom!

Sent by Irene C | 2:44 PM ET | 05-24-2007

A caller earlier suggested lowering the tailgate on one's truck, thereby reducing drag. This is not the case, in fact this increases drag. When the tailgate is raised, an air-pocket is created that streamlines the vehicle.

Sent by Ric Jones | 2:44 PM ET | 05-24-2007

I am very certain that you get better mileage in a pick up without a cap with the tail gate up. Tailgate up seals aerodynamically the cargo area and creates less drag vortex. This is true with an empty cargo bed. It is my understanding that a stubby rear end will also get better mileage than a pointy, tapered rear end ala Corvette design from the 60's. I forget the guy's name......

Sent by Mark | 2:44 PM ET | 05-24-2007

You can increase your consumption of domestic food products (from American farmers), improve your health, have fun, and save all your gas by riding a bike.

Sent by Brad Schwie | 2:45 PM ET | 05-24-2007

I get very good mileage up to 49 miles per gallon. I drive a Toyota corolla.
Tricks I use to save gas:
Have a small economical car.
Drive smoothly.
Use cruise control.
Minimize rough and quick acceleration .
Do not go past 30 revoultions
Drive below the speed limit (75) which is too high to save gas. I drive at 60 mh .
It does make a difference . People could make a difference but they do not implement the suggested tricks. If only their pocket was affected it woul be ok but we must think about the reserves of oil the same way we must be concerned about the environment and global warming.
MArgarita

Sent by Margarita Cordoba | 2:45 PM ET | 05-24-2007

My car, a BMW 318i stick shift with a 1.89 liter engine, has a gauge which gives a continual reading of fuel economy. Of course I've watched it quite a bit over the couple years I've owned it and have found that it's absolutely *not true* that driving more slowly yields better gas mileage. It's often the case that I get higher MPGs at 75 or 80 mph than 60 or 65mph. The pivotal condition is that the tachometer registers a bit over 3krpm. At this rate I can get around 40 MPG. Of course if I'm in a different gear at the same rpm rate I can get the same mileage, e.g., I can get 40 MPG going 35mph if the tach reads a bit over 3krpm.

So if you see me on the highway whizzing past you going 80, don't scowl and curse. I'm saving gas.

Sent by ken | 2:46 PM ET | 05-24-2007

RE: tailgates. I remember reading something a few years back, when Toyota was getting into the fullsize truck market, that they did extensive testing and found the benefit of lowering the tailgate to be anywhere from negligible to unmeasurable. Their conclusions were that the air hitting the tailgate is not smooth, laminar airflow, but is already tumbling from dropping off the back of the cab. I've also read that a light, aerodynamic camper shell can improve mileage.

Sent by Wade | 2:46 PM ET | 05-24-2007

In the past, people would calculate their gas mileage based on the number of miles traveled and the amount of gas put into a car at each fill up. These
days however, most cars have a display which purports to tell the driver the average gas mileage.

My concern is that these displays may not always be accurate, but rather inflate the actual gas mileage which is reported to the driver, thus leading to
a feeling of getting good gas mileage when indeed the gas mileage is not that good.

As an example, we own a 2004 Toyota Camry in which the display reports the average gas mileage to be consistently and reproducibly 20-25% higher than the
actual mileage when measured at the pump. We also know many other people with similar Camry's who have experienced this same degree of overestimating
the average gas mileage by the display.

Thus, I am now wary when people report to be getting "great gas mileage" since now most people are basing their measure of gas mileage on the display rather than actual mileage as measured at the pump.

Sent by Pete Torpey | 2:49 PM ET | 05-24-2007

I have a new Prius and I am wondering about the emissions vs. the mileage. Do the emisions go up when the gas mileage goes down? I am averaging @ 45 mpg in the city because most of my trips are pretty short and the dealer said I would not get the highest mileage until the engine is "warmed up". Also, living in Minnesota, we have a high level of Ethanol/additives in our gas, with a governor who is pushing for E85 (85% ethanol) implementation in the state. How does this affect the gas mileage in hybrids? Is the effect the same between hybrids and non hybrids? Pretty technical stuff, but I would love to know the answers to these questions. Also, did anyone see the Discovery Channel program on the future of alternative vehicles that ended with the Air Car? Does anyone think this is really a feasible and manufacturable car? It sure was cool!!

Sent by Clea | 2:51 PM ET | 05-24-2007

RE: aerodynamic drag. Take off the roof top carriers when they are not being used. Any sort of cross piece will create drag and lower gas milage at higher speeds.

Also, minor tip, turn-off the $%^&*( fog lights when there is no fog and you are driving at higher speeds. Lights sap minor amounts of energy but with the number I've seen on, it could add up. Fog lights were designed for low speed driving in a fog (why do you suppose they are called "fog lights") and really should be used only when the headlights cause too much light back scatter from fog droplets. At highway speeds they provide no benefit and only blind other drivers.

Sent by Phil Fischer | 2:54 PM ET | 05-24-2007

Anyone try any of the synthetic additives
to regular oil, or switch completely from
regular to synthetic oil, and notice a
difference in gas mileage? Do these
actually work, and pay for themselves in
increased mpg?

Sent by Tom Litow | 2:55 PM ET | 05-24-2007

Has anyone else had results like Ken's, with faster speeds yielding BETTER mileage?? I've certainly found that driving 55-65 is much more efficient for my 1999 Honda Civic.

Sent by Matt | 2:56 PM ET | 05-24-2007

Mpg displays which give real time feedback on gas usage should be mandatory for all new vehicles.

Sent by Sue | 2:57 PM ET | 05-24-2007

This may not save the typical driver much, but I've changed my habit of adjusting, mirrors, putting seatbelt and radio on etc. after starting the engine to BEFORE starting. It probably would benefit the environment significantly if everyone made this a habit.

Sent by Stuart Hoffmann | 3:01 PM ET | 05-24-2007

Conservation is counter productive in this situation. The only savings realized, both in dollars and environmental impact, are extremely short term. To illustrate: say everyone cuts their fuel usage by 20%, figuring that is discretionary driving, while the remaining 80% is necessasry. For a short while there will be a 20% reduction in expense as well as generated pollution. However, the oil companies (and those associated) will not be willing to live with a 20% reduction in revenues. They know we have to have the fuel for the non-discretionary 80%, so they, having a captive consumer, will raise the rates to cover their loss and once again be back to their target profit margin. And they will be loving it, because their supplies will last 20% longer. So in the long run, we will pay more, longer, and though the pollution may decrease in current generation, it will be released over a longer period of time. You can extend this idea to the extreme, using very little fuel for a very long period, at a very high cost.

The only answer is to stop using oil, and create real competition between fuel sources. Competition between oil companies is an illusion. We are a captive market. Without real alternatives there is no real competition. The oil companies determine their pricing structures by finding "what the market will bare" not by the "law of supply and demand" (which only works in a truly competitive market). Stop conserving and change.

Sent by Brian White | 3:02 PM ET | 05-24-2007

Move to a small town. When the drive to work is only a mile, you could use a bike. Corporations are moving investment to small towns because the cost of living is lower, so the salaries they offer are doable.

Sent by Day Brown | 3:22 PM ET | 05-24-2007

As mentioned on-air, clean/replace your air filter.

Also, regularly waxing the finish will, even minimally, reduce wind drag.

Have your windows tinted to what is legal in your state - will reduce interior temps, thereby reducing the work required of your AC system.

If you live where it is cold in winter, instead of running the engine to warm up the car in the morning, get an electric block heater installed and plug it into a timer so it turns on an hour before you leave in the morning - instant heat, no gas used, and much easier on the environment pollution-wise.

I wish municipalities would get their act together regarding synchronous timing of stop lights along main roads. It's a joy to drive at the speed limit and get endless green lights, plus it saves a tremendous amount of gas for every vehicle on that road. It also lowers your blood pressure.

Sent by David | 3:26 PM ET | 05-24-2007

The idea of using nitrogen in the tires instead of air was briefly discussed on the air without an explanation of its benefits. Tires inflated with nitrogen do not change temperature when they get hot. Nitrogen does not leak through the tire walls as air does. Proper tire inflation is always mentioned as very important to mileage. So nitrogen filled tires remain at their optimum pressure for an almost unlimited amount of time and the tire life is extended because the tires don't "heat cycle". One way to convert tires to nitrogen is to remove the valve stem and fill the tires three times with nitrogen. This purges the air to all extents and purposes. Then replace the valve stem and do the final fill. Small bottles of nitrogen are available for backup fills--which are very rarely needed.

Sent by Myra Lader | 3:57 PM ET | 05-24-2007

Anybody remember all the gas we saved when we reduced all the speed limits to 55 mph. Reduced accidents and fatalities too. Hmm. Maybe we should try that again...

Sent by Cindy Reese | 4:12 PM ET | 05-24-2007

Use 93 Octane fuel!

The cost is now about 7% more expensive to fill your tank but the gained fuel efficiency is between 15-25%. YMMV.

Try using the fill-at-the-pump method --I will now explain) to check this if you do not believe.

The next time you fill your tank with regular (87 Octane), fill it until it automatically cuts off and do not top off. ASIDE: topping off reduces your fuel efficiency by interfering with the vapour-return system in addition to skewing the result of the mileage calculation.

Zero your trip meter or note your odometer reading. When your tank is almost empty, (wait until the light comes on or the needle is actually on "E"), fill up totally again --with no topping off-- with premium (93 octane).

Divide the reading on your trip meter (or difference on your odometer) by the amount of fuel you just added. That is the amount of mile you drove per gallon of regular. Reset your trip meter or note odometer again.

When the tank is near empty again, refill again as before --no topping off-- and do the calculation again. This is your MPG on premium.

It is important to do this experiment during normal workweeks. If you took that trip to Orlando on regular fuel but battled the rush-hour all week on premium, you may think that premium decreased your mileage :-0 !

If you are planning a long trip, (600+ miles) you can do this on day one. We assume all driving is highway and mostly flat. That, too, may not be true.

My '82 Honda Accord CVCC showed a 20% increase, my 94 Nissan Quest GXE showed a 25% increase and my '07 Toyota Camry showed a 16% increase.

Certain vehicles recomend high octane fuel under normal conditions so this is moot :-( (as with my '84 Toyota Celica). The good news is that it also makes your engine waste less heat, reduces pinging and knocking, burns cleaner (less harmful emmisions) and saves you money.

You may think you spending more as it will cost more to fill your tank (approx 7%) but it will cost less per week as you will fill less often by taking you more miles per tank (approx 20% more miles) for approximately 13% savings. Again, YMMV.

Sent by Karim | 8:58 PM ET | 05-24-2007

Has anyone ever thought of the glaringly obvious? Don't idle your car when you're not driving. It gets ZERO miles per gallon. It creates wear and tear on your engine, fouls up your engine oil, and pollutes twice as much driving, which means that you're breathing it yourself.

Idling is the wrong way to warm up a car, because it doesn't lubricate the engine parts. This idea of stopping and restarting as bad for your car was for 25 years ago, before cars used fuel injection.

Sent by Michael Modica | 11:06 PM ET | 05-24-2007

I caught a part of your show on ways to save gas yesterday. I was itching to call in but did not have a phone. I have installed a little known after market Revolutionary Spark Plug - every one should check it out. It is used in Police fleets (Fox did a story on it abt 3 weeks ago). The plug is called Halo by LSG BRISK LLC. It improves gas mileage and reduces gas emissions by 30%. When changing your plug - do check out the options - don't just let you mechanic put in the same plug as you had before.
Garima

Sent by Garima Kamo | 8:02 AM ET | 05-25-2007

As an ASE certified master automobile and heavy truck technician, I was appalled by the ignorance of the basics of gasoline engine operation displayed by both guests, as well as by their reluctance to debunk many of the rumors presented. The part of the gasoline engine that limits the airflow into the engine is the throttle plate. The air filter has an effect only at wide open throttle, thus its condition will have no effect on most normal driving. In a modern fuel injected engine, the amount of fuel injected is always in proportion to the air entering the engine. If more air gets in, as at open throttle, more fuel is used. If a restricted air filter limits air flow, the car may actually use less fuel at wide open throttle. A dirty air filter will waste fuel if the vehicle is equipped with a carburetor, as was the case on many cars years ago.

I was pleased that your guest Amy did make it very clear that the driver of the car is in control of the fuel used. Smother driving, shutting off the car when ever possible, and walking or taking the bus will save far more fuel than any gadget or additive. Many of the things being sold to save fuel will not save enough money to pay for themselves even if they did work as advertised. I noticed in reading the other posts here that tire pressure was discussed. I would not recommend over inflating any tire, but simply making sure all of the tires have the proper amount of air will avoid unnecessary fuel use and has a safety benefit as well.

Sent by Robert Bottger | 8:22 AM ET | 05-25-2007

All I know is that I love my Diesel VW... get about 40 miles per gallon in town w/o being crammed in tiny hybrid or some wired 3-wheeled contraption???

Sent by some1else2day | 3:13 PM ET | 05-28-2007

Chris Groner Wrote: "Also, why is the tax credit for hybrids being phased out when we need cars with better mileage? Doesn't make sense."

Actually, having a tax credit for a high fuel economy hybrid makes ZERO sense.

The only thing that makes less sense is the tax credit our Congress afforded to upscale soccer moms who drop off their toddler at the local Montessori in Ford Excursions or Chevrolet Tahoes.

Hybrids are rapidly maturing technology that have been selling well. My tax dollars should have to help some yuppie buy his car.

Sent by Rick Evans | 2:54 PM ET | 05-29-2007