heard that low or 0% nitro fuel works well with these engines and makes them run alot cooler!
you probably will need a !QUOT!on board!QUOT! glow system for the engine to be able to idle well on low or 0% nitro ... you could probably set this of the throttle servo horn so it only powers the glow plug at around idle?

i have been having clutch problem's! i used a 2shoe clutch like yours which worked but i decided to buy a 3shoe! it seams like the springs in it are too hard which means its slipping really bad and not much power is gettting to the wheels! i have tryed bending to springs to see if it will loosen them but I'm now waiting for a new starter!

i have a fan on mine for cooling (see picture) the only problem is its not reliable! the belts don't last long before snapping and you wont want that to happen while your driving around because you wont be able to know it has happened and your engine would soon overheat!

yes i have heard of the OS fs car engines there exactly the same as the airplane version apart from they have harder valve springs! (mine is a airplane one with stiffer springs)
if you go on to the towerhobbys website you will see that almost all the part numbers on the OS fs car are the same as the OS fs plane

sounds like you have been a lucky one to have not had any probblems so far

ps: i will upload some videos of my car running the 4stroke later today!