Deceptive, isn't it?! En radiobil is definitely a bumper car/dodgem, so-called I think because the tall antenna on the back of the car looked to someone like a radio antenna, once upon a time?
Remote-controlled cars, as in the toys/hobby things, are mostly just referred to as RC biler, or radiostyrte biler.
"bilradio" = car radio
"radiobil" = bumper car
(Just looking at the word for the first time, I translated in it my head as "car radio," as in a radio designed to be put into a car. So naturally, I had to look it up to see what the actual Norwegian word was. Turns out, I wasn't that far off.)