hi neil...like the battery tray. just a quick note to make you aware that r/c heli controllers use ccpm mixing, if this can be turned off with the dx6i(which i should imagine you can), if not you got a problem using it with a car.

the ccpm mixing mixes the cyclic controls with the throttle i.e when throttle is increased all 3 servos on the head of the heli will all lift at the same time to increase the blade pitch, so if one cyclic control would be your steering then a throttle increase would also self steer the car.
best to find out before you purchase . if you cant find out p.m me and ill ask the guys on the heli forum who have dx6i if mixing can be deactivated.
bye neil...