I'm not sure if I'd really want a child that young on this ride.
The foot pedal is VERY hard to push in. Even my 11-year old has difficulty with it, and I usually end up pushing it in while he drives.
Trying to drive and hold on to an 18-month old would be difficult. Its a bit herky-jerky to steer, and you can find yourself 'back and forth' a bit if you don't control the wheel very well. The straps that hold you in are not even close to regular seat belts, and I can't imagine that the head 'catchers' are low enough for a child that small; any sudden stop and his head jams into the hard plastic seat.
Finally...even though there are plenty of signs that say "Do not bump car ahead of you"...it happens. Its not pleasant.