greenpower dude reloaded. I had a list of sites that included specs and a parts shop for your race series. You posted some links also. Could you post information so that we can consider solutions based on specs? I remember that motors, switching, batteries and "throttles" were standardized ... but what is open to electrical engineering? ( Like I even know what that means.)
I remember a Lola CANAM car that used your rounded front end. It generated so much lift they had to put a wing on it. Could that contribute to overall drag. There was an aero F1T thread on a model race car competition. Might be worth looking up. A mild undertray tunnel with a duct to cool the engine ( if you can feel the drop... it's severe) with a rear defuser. These could be engineered into the current body. Another bit of annoying advice and commentary. Recess the driver below the upper profile body surface and put a large clear plastic windshield following the current front end profile. Definitely consider new front aero. Allard Le Mans car has some inspirations. Inspires me anyway. But then I'm not making bodyplugs and doing actual design and construction. (Sigh)
EDIT - Then again, if the front body profile generates lift - it would generate downforce if used in the rear fender profile.
your right they do lose efficiency when hot but I have managed to get it running pretty cool now. I have no information on how much of a drop there is, but its noticable.