I generally don't let the RPM's get too high unless I really need them to.

Any tips for new good habits I could start?

 

The key on the manual is to get into 6th gear as gently as possible and leave it there as long as possible. Leaving it in 6th is the most important.

 

Yes, upshifting as soon as the auto will let you and getting into 6th ASAP gives me my best mileage. Cruising along at 60 mph in 6th at 2000 rpm gives great mileage.

 

Actually, you get the best mileage in the R53s cruizing in 4th gear going 25-30 MPH. This is due to 3rd and 4th gear having a 4.10 equivalent rear end gear ratio as opposed to the other gears having a rear end ratio equivalent of 2.74. I've seen 50+ MPG doing this. Even though it's a taller gear ratio, it keeps the engine from having to pull even the tiniest amount of boost. Of course, no one wants to drive that slow all the time.

Higher RPMs does not necessarily mean less gas mileage. As an example... when I'm cruizing 45 MPH going up a hill to a bridge, I downshift from 6th to 5th gear. It pulls less on boost and actually helps save fuel (i.e. the average MPG goes down slower).