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by Rahul 02 May 2008, 22:30
31. Do you need to inflate your tires up to the numbers shown on a tire sidewall?
No... Tire maker stamps *maximum allowed* pressure there. Only your car maker knows what pressure is right for your car. And it is always lower than "maximum allowed". Even though over-inflating your tires will improve your gas mileage, there are a number of major downsides. With over-inflated tires, you will experience much faster tread wear in the middle of your tires. That extra wear will have you buying new set of tires much earlier than you might expect. The cost of new tires will wipe out any savings you might otherwise realize from gas savings. Also, over-inflating your tires makes them much harder and will cause a very uncomfortable ride... rough and bumpy. Finally, if you over inflate your tires, you'll have worse traction, significantly impairing your safety. Marginal savings (if any at all) will not compensate for the significant loss in safety and comfort.

32. Do you need to use gas savers? Tornado, Ramjet, Cyclone, and other gas saving devices?
Nope... gas saving devices are not just a myth – they are an outright scam. Shoot the messenger who suggests you should buy a gas saver. I'm serious. Testing such devices was one of my responsibilities when I worked in car engine research field, and not a single device out of the dozens I happened to test, worked. Federal Trade Commission agrees, too. Do yourself a favor, stay away from such things.

33. Do you need to use higher octane fuel or octane booster?
As a general rule - no... if your owner's manual says to use regular, you are better off using regular. You will not get better mileage with premium. Computers control all of a modern cars' engine functions. Each models computer is programmed to achieve maximum fuel efficiency for that specific design. There are exceptions though. Some European and Japanese car makers install high performance engines, originally designed to run on premium gas, in selected American market models. They then turn around and de-tune those engines to run on regular gas without detonation problems. I don't know why they are doing this - it's probably driven by cheaper production costs, certainly cheaper than modifying the combustion chamber. I haven't seen any of these cars myself, but people do report them on forums. If you feed premium to one of these modified cars, you will get somewhat better mileage, but still, probably not enough to offset the extra cost of premium.