[colliewagon]

I mostly drive to work on a two lane State Highway with a 70 mph speed limit. Late at night, it's often quiet enough for me to pick whatever speed I want (and I've also noticed that a lot of the late night traffic is also going closer to 60, so I think the high gas prices are causing others to drive for higher mileage as well).

But during high traffic periods, it's not really safe to try to go 55 when everyone else is going 75. A string of cars line up behind you, then people get impatient and take stupid chances trying to get around you. The road has just enough curves and blind spots for this to be dangerous - which doesn't stop people from trying it.

Anyway, I'm trying to work out a "medium" cruising speed, that strikes a good balance between mileage and not going too slow and blocking traffic. The tachometer is hovering on both sides of 3000 rpm at various cruising speeds. Obviously, slower is better for mileage. But are there any special rpm's to stay below? At what point does the VTEC kick in, and how much does it affect mileage?