Our daughter, who is currently 22 years old, still gives us light hearted abuse over the fact that she is emotionally scarred from being denied the "Barbie Jeep" in her younger years. We always found just the right thing to say, whilst addressing the problem when she was little. Since we were big fans of treating our little spawn as the princess she was, we just told her, "I'm sorry sweetie, we have plenty of money to buy you a Barbie Jeep, but it is never going to happen". When she would beg and ask why? we would look he in the eye and tell her, "well, obviously that little girl's mommy and daddy must love her more".
This helped her to develop the wicked sense of dry humor that runs in our blood. She was recently discussing a family friend who devoted her life to taking care of her elderly father. We told her that we expected this devotion if the need should ever arise. She responded in a flash with, " not happening, remember the Barbie jeep?"
As for the OP, the whole idea of letting barely mobile toddlers "behind the wheel" of a slow, plastic wheeled toy pales in comparison to a lot of the local rednecks in these parts, who think that getting junior on a dirt motorcycle or miniature four wheeler, at five years old is a great idea. What could go wrong, eh?