I drive at speeds to optimize my mpg and use cruise control often. In town I try to drive a sustained 45mph while on the highway I drive a flat 60mph. I get great fuel economy, much to the chagrin of my fellow drivers because they're forced to pass me.
I am a slow driver and I don't mind. By slow, I mean a maximum of 5 over the speed limit. I received one speeding ticket a few years ago because I was late and was trying to make up time. Well after paying a $185 fine I decided it would be wiser to organize my life a bit and stop always leaving late. That and I figure what is the rush? Not much is worth the risk of another big speeding fine.
When you combine high gas prices with the many stop lights in the city, driving fast is a waste of time and fuel for me. So I tend to stick to the posted speed limits whenever i am driving. Add to that the fact that on our highways the traffic police is always out at different sections.