Jamie knew that Billy was quite smart, but never realized he was capable of being able to create a flying car - well, modify one to fly, anyway. Whichever way you put it, he's impressed. He walks around to the back to get a better look at the apparatus.

"So, ye are saying that that fuel accelerator-thing allows ye to actually lets the car go in the air and fly like ye would in those cars on that one Earth we visited?"

There's a speculative glance upward at that. "I wonder...would ye have enough room in here to test it out?"