There is always some confusion among guests as to whether the child is allowed to drive or not, especially since there is a height restriction on the ride. DH saw this and backed out of the line, thinking our DS2 couldn't ride. The sign says a child must be X tall in order to ride solo!
So DS6 drove with DH as a passenger, and DS2 drove (wildly, I might add! ) with me as a passenger. The cars are on a track, but the steering wheel does maneuver the car left and right a bit along the track.
My parents are both pooh sized individuals and they rode together in one car. I am average size (by no means skinny) and I rode fine in a car with my 2 5yos. So I don't think you should have any problems with 1 and 1.
This was my 6 year old daughters fave and we must have rode it ten times! One note: For the full-on fun, try it at night at least once! We had a blast! We were screaming and having fun at her 6 yo driving skills and on the bridge above us my 23 yo son and his gf went by with such a look on their faces at our screaming. I got the BEST picture of that!!! Much silly fun for all!