[MrForbes]

If you have the "2007 Guidelines_Tips_Good Practices_RevA.pdf" file, look on page 8 at the little chart of the CIM motor, you'll see that max efficiency is somewhere around 80% of max speed.

I'd shoot for somewhere in that neighborhood.

Also the current that the motor draws is proportional to the mechanical load on it. So, if you're cruising along at 80% of max speed, you won't be using much current...unless you're also pushing 3 other robots across the field at the same time!