...rides in the ambulance... In any case it is irrelevant as this is not a question of who is driving but one of just properly translating the sentence. DL is not concern with factual reality.
The doctor doesn't drive the ambulance, he drives IN the ambulance
How can you drive 'in' something? Do you mean 'ride'? Driving is the act of controlling a vehicle (or less often, livestock).
Why was "the doctor rides in an ambulance" rejected? "riding" was given as a translation of "koerer" in the drop-down menu. I have reported it, for what that's worth ...