My feeling is as much as possible keep the engine turning at a steady rate that feels right. I ride the clutch a little while I run up the revs and shifting down i boot the engine out of it's idle before engaging the lower gear. Doesn't seem to affect fuel economy and the car has a much smoother ride. My own guess is that 2600-2800 is about right but I've never had a tach to test it. Judging from the tach in the 190 it might be more like 2300. Just don't try to go faster when you accelerate!