Hope it is ok to review this old thread. Have build this MOC a while ago and found it fun but very difficult to steer. When the servo motor became available, I have replaced the M motor with the servo motor. This has been a bit of a challenge because the car is very compact because there was not much space for the larger servo motor and because I did not want to significantly change the way the mini crawler looks. With this modification, it is amazing - 4WD, two gears, RTC steering, all in a tiny nice looking package. Thanks for sharing this, ghostever!