A little something I just saw, kind of interesting. I know I've heard some of these things here, including some of the false ones, as gas-pumping tips.

http://www.boston.com/business/perso...leconomymyths/

 

Very interesting, thanks Stephen! I find two of the items strange. The dirty air filter won't hurt fuel economy? And higher tire pressues won't help?

 

Well the dirty air filter one I wasn't surprised at, I'd heard that one before. I don't know how it works, but I trust the guys who say it's so more than I trust me, hehe. And the tire pressure I did get wrong, because I'd figure reduced surface contacting the pavement would reduce tire/surface resistance. I dunno...

 

The tire pressure question is a bit of a trick question. At some point it will start to not hurt your gas mileage, but over inflating them SOME WILL help your gas mileage because it will reduce rolling resistance, and they don't define what "properly" is, if I fill to manufacturer recommended instead of tire max psi i will loose ~3 MPG

 

The dirty air filter really only becomes a problem at wide open throttle (unless of course it's so dirty that it's clogged). When you're driving for economy, you tend to keep the rpm's low, which doesn't suck as much air.

Robb

 

This one is incorrect, from page 15 regarding higher tire pressure:

"Popular Mechanics has also road tested this theory and concluded that the gas mileage doesn't improve."

Popular Mechanics have never been gas mizers anyway

-Steve

 

A while back I was watching a news program that was going over the myths. They also concluded that increasing the tire pressure was not helpful. The important part of their statement was why.

They used the rationale that the increased pressure, resulting in less surface resistance, increased fuel economy but not to a level where the potential safety risks due to less surface resistance were worth the savings.

That said, I keep my tires at 40 psi all around and I have not had a problem on snow, ice, or water.

 

Dirty air filters used to increase gas consumption back in the days of carburetors. Blocking the air flow before the carb would increase the richness, acting just like the choke.

With modern fuel injected cars, the air/fuel mixture is precisely adjusted, so a dirty air filter will not cause an overly rich mixture, but maximum flow is reduced, which means less horsepower. Reducing the maximum power might actually decrease fuel consumption, but I haven't seen any claims about this.