You wont go far wrong with the Spektrum H6040 or the Savox 1258tg
there both excellent servos and almost the the same servo!
heres the spec's
http://www.servoshop.co.uk/index.php...040&area=Servo
http://www.servoshop.co.uk/index.php?srch=1258
or maybe have a look at the Savox 1257tg for a 2wd car
http://www.servoshop.co.uk/index.php?srch=1257