Comments on: How to Improve Your Gas Mileage (and How Not To)

By: jan kissel

jan kissel — Wed, 08 Oct 2008 13:23:14 +0000

Would like to know if, when driving 18 miles to my club, am I better off to take the tollroad ($1.50 each way) and drive 65 mph or the stop-and-go route, no toll? My PT Cruiser gets 16-18 mpg. Yuk. Also, is it more economical to have AC fan higher or temp cooler? Or is there no difference?

Many thanks.

By: Madhava Gosh

Madhava Gosh — Thu, 24 Jul 2008 13:02:41 +0000

About accelerating — the old truckers saying is accelerate as if there were an egg between your foot and the gas pedal.

Anticipating traffic light changes in light traffic can increase mileage. Brake before you have to and creep up to the light so you are still rolling instead of driving up and then braking to a stop helps a lot.

By: nickel

nickel — Fri, 18 Jul 2008 16:45:15 +0000

drewzr: That’s what I’ve always thought, too. However, based on CR’s test data, at least for the car they tested and the conditions they tested it under, there’s no difference. Of course, the best of all possible worlds is windows up and AC off, which is what you’re essentially doing when you recirculate the cool air after shutting down the AC (I do this, too).

By: drewzr

drewzr — Fri, 18 Jul 2008 16:30:53 +0000

About myth #2, opening windows is better in city traffic, but on the highway it’s better to use the air conditioning. Or, you could do what I do and use the vent. If it’s too hot for that, I usually set the vent to ‘recirculate’ and turn the AC on until it’s cold enough, then turn it off. When it gets too warm again, i turn it back on.

By: Boston

Boston — Mon, 30 Jun 2008 02:14:43 +0000

I like the point about tires. I agree with Scott and wonder if there is some sort of system for rating tires. I actually am in the market for a new set of tires so if I find something I’ll be sure to post it. Thanks for the ideas.

By: Scott

Scott — Wed, 25 Jun 2008 20:28:58 +0000

Is there a rating system for finding tires with the best (least) rolling resistance? I have the Michelin Energy tires which are supposed to have been designed with this in mind, but I was wondering how one might compare brands? Great list!

By: snowed in

snowed in — Wed, 25 Jun 2008 13:35:52 +0000

The problem with point #2 is that there are a lot of people who interpret “avoid rapid acceleration” to mean that they should creep away slowly from a traffic light rather than getting up to speed. Among other things, this tends to cause the people behind them to brake, if they were accelerating at, you know, a normal pace.

The trick is to find the happy medium: don’t burn rubber when the light turns green, but do move smoothly into higher gear at a good pace.

By: Ashley Barton

Ashley Barton — Mon, 23 Jun 2008 22:24:19 +0000

There is an import fact missing from myth #1 (morning fillups). While filling stations tanks are underground, the tanks where fuel trucks get the gas that they deliver to the filling station are above ground. I work in this industry and the fuel terminals, where gas stations buy the gas they sell, calculate the net quantity that they charge to the filling station by compensating for variations in temperature to one-tenth of a degree.

So if gas has sat overnight in an underground tank, it cools to ground temperature and is then more dense giving the buyer more energy per gallon. If you buy later in the day, a truck may have recently delivered “warm” fuel to the station, with less energy per gallon.

By: FredW

FredW — Sat, 21 Jun 2008 10:33:50 +0000

Nickle, great lineup. If I may, Paul over at Catskill house had a similar blog not to long ago where he showed the math behind slowing down. Several good comments to that post as well. Have a look.
http://www.catskillhouse.us/bl.....mment-3263

Fred.

By: L

Thu, 19 Jun 2008 19:44:24 +0000

Regarding the morning fill-ups, here in BC the pumps are calibrated- there is a little sticker that reads “volume corrected to 15 degrees”
Do you not have that in the US?

By: mapgirl

mapgirl — Thu, 19 Jun 2008 17:21:30 +0000

Moose- Most modern cars have a computer that will adjust the fuel mix so there is no need to ‘warm up’ an engine anymore.

FWIW, if you are going idle for more than a minute, you can turn your engine off.

If you want to know more, try CarTalk at Cars.com. They frequently answer gas mileage questions and that’s where I learned those two things.

Nickel- I agree that steady ground temperature means that morning fill ups are a myth, but when the ambient temperature fluctuates 40-50 degrees from day to night (like in the desert), it might actually be true if the ground temp is also moving say, 30 degrees. Has anyone actually studied this?

By: Moose

Moose — Thu, 19 Jun 2008 04:44:45 +0000

I recently stopped starting our car in the morning to let it “warm up” before taking off for the day. Well to be more accurate, I stopped letting it run for 5-10 minutes and instead cut the time down to about 2-3 minutes. With gas prices going crazy, I figured even if it saved me a little bit of gas it was worth it. Any opinions if idling really causes major gas loss?

By: john

john — Thu, 19 Jun 2008 00:44:00 +0000

another reason not to speed is speeding tickets, which will cost a couple hundred bucks and potentially raise your insurance!

By: VicfromATL

VicfromATL — Wed, 18 Jun 2008 21:19:24 +0000

I think Morningfillups should make a difference as even the ground/underground cools over night.

In my experience, in city traffic..Air conditioning has an effect (by couple of miles/gallon) on mileage.

By: Michael Campbell

Michael Campbell — Wed, 18 Jun 2008 20:53:38 +0000

Couple points here.

You don’t change air filters for mileage, you change them to keep grunge and dirt out of your engine. Change them when the manufacturer recommends.

Also, driving is not a game. It’s not a competition to see who can beat whom with the penny savings. It’s a serious $#@! activity, and the hypermileridiots who turn off their cars to save a dime every 100 miles by threatening their own, and others safety deserve a special place in road rage hell.

Lastly, and I know this is a nit, but premium fuel may actually HELP /mileage/, but not enough to outweigh the costs. (So I agree with the spirit of the tip, just not the letter.) Again, put in what your car manufacturer recommends. THEY actually do test that stuff out and not rely on anecdotes.

By: budgetsaresexy

budgetsaresexy — Wed, 18 Jun 2008 20:40:55 +0000

Oh man, thanks for clarifying myth #3 – the dirty air filter one. I’m always hearing that from the mechanic and tempted each time

I do change it, don’t get me wrong, but i didn’t think it was 100% necessary during EVERY oil change.

By: "Mo" Money

"Mo" Money — Wed, 18 Jun 2008 19:54:29 +0000

All good tips. Something all drivers can implement. Thanks for the myths also.

By: nickel

nickel — Wed, 18 Jun 2008 19:36:14 +0000

Yeah, what I’ve read seems to agree with Aaron’s thoughts. Hypermilers tend to focus on acceleration when going downhill, and are content to lose speed uphill rather than racing the engine to maintain speed while working against gravity.

By: Aaron

Aaron — Wed, 18 Jun 2008 18:18:07 +0000

Good post nickel. I can vouch for 1 & 2 also. I went from averaging about 30MPG to 36MPG in my xB just by trying to be mindful of my speed and acceleration. Slowing down early for lights (coasting) helps too.

KITTY- My reading on the hypermilage sites leads me to believe that steady pressure on the gas pedal is better than a steady speed. You may only go 50 on the uphills, but you’ll go 75 on the downhills. Seems like it may not work, but I think it does.

By: kitty

kitty — Wed, 18 Jun 2008 17:38:24 +0000

Any tips for driving on a mountain parkway that goes up and down a lot? It seem to me that in this conditions, maintaining a constant speed may not be a good idea as it would entail pressing hard on gas when you go up and breaking when you go down. Wouldn’t allowing the car to slow down when going up and allowing it to speed up naturally when going down would make more sense in these conditions?