Which is better mileage-wise? Driving faster or slower? There are many places that I go for which there are many ways to go to get there. Some of those involve the perimeter where the speed limit is 65. Otherwise the speed limit is 35. So my question is this: Which is cheaper in fuel, going X miles at 35 mph or 65 mph?
You get better mileage driving the same speed. Eg if you go 35MPH and start/stop at lights or for traffic mileage suffers more than steady 65MPH. However driving 35 MPH steady gives the best mileage since wind resistance/friction works against your engine.
If there are no traffic lights, and you can drive without stopping, slower is better. However, highway mileage is usually much better than city mileage because you spend more time moving. In the city you stop often, and sitting at a light or a stop sign you are getting ZERO mpg.