FACT:
Your vehicle gets better gas milage on the highway, than in does in the city.
FICTION:
You get better gas milage by driving slower.
Simply put, you want to get your vehicle's transmission into it's highest gear (overdrive for most new cars) as quickly as possible, so that you can cover as many miles as possible while the engine is spinning at it's lowest speed.
Driving at low speeds, the vehicles ECU (Engine Control Unit a.k.a. the computer) working in conjuction with the TCU (Transmission Control Unit) doesn't allow the engine to "lug", or to operate a low speed in a high gear (which, by the way, you can do with a manual transmission). So, the engine is forced to use more fuel in order to maintain a higher engine speed at a lower vehicle speed, lowering fuel economy.
So, something to think about: in these days of $4/gallon gasoline, federal, state, and local governments should reconsider the speed limits on their roads, so that the country can conserve fuel!
