Honestly, you kinda have to get lucky with the placement of the cans and hope you can get all three in time. The cans reset every 20-30 seconds i think so just wait until they get real close to the entrance.
Otherwise, theres not really anyway besides buying other car magics.
Wish you the best of luck and hope this helps!
I am having the same problem! I am on the Adventure Through Inner Space Quest (Easy), and I earned the "Autopia Race Blue" Magic ... and when I click it, a car appears, but it does not go on the race track to let me click on any of the gas cans. My car vanishes in a few seconds. Then I have to wait a while before I can try again, and still nothing happens. Is there a glitch? Or am I missing a step? I'm new to the game. I'm just trying to enjoy it, but I'm stuck on this quest. But finding no solutions.