A: The fuel emissions canister is filled with charcoal, which traps and stores fuel vapors to keep them from escaping into the air while the car is parked. When you start the engine, a valve opens to allow those vapors to get sucked into the engine emptying the canister, readying if for the next time.
If you keep pumping gas once the nozzle clicks off, you may be forcing liquid into the canister. After a while, as it vaporizes, the charcoal dries out, but not always. A warning to all drivers: Do not top off your tank.
A: Fuel usage depends on several factors. When you lift briefly, the fuel injectors continue to pulse. But at a predetermined engine speed (usually around 1,000-1,500 rpm) the fuel injection shuts off until the engine speed drops or you step back on the gas. If your car has an instantaneous fuel economy display, you may see it climb up to 99 mpg during a long coast.
During this time, the engine is still turning, and hence so is the oil pump. No metal to metal contact. Ditto for the transmission.
A: You can thank the GPS system for tracking your speed and reporting the posted speed limit. You may notice that the information goes away when you are going through a tunnel.
A: When you replace tires, you want them to all be the same size and age. Leave the spare alone, but check its pressure once in a while so that it is not flat if you need to use it. Although it may have some age on it, the spare will likely get you to a service facility.
A: Just keep on doing what you have been doing. Well, maybe you could get a bottle of Champagne and a birthday cake to celebrate.
ABOUT THE WRITER
Bob Weber is a writer and mechanic who became an ASE-certified Master Automobile Technician in 1976. He maintains this status by seeking certification every five years. Weber’s work appears in professional trade magazines and other consumer publications. His writing also appears in automotive trade publications, Consumer Guide, and Consumers Digest.