The design flaw is that the wind up turn crank is longer than it should be and is at least 2/16th of an inch below the wheels and so the turn crank hits the table that this would be riding on. So to me that is definitely a design flaw. The wind up crank works and the car does go and then pops up a little when the crank hits the table. The back wheels are the one that go around when you turn the crank. This is in excellent condition but the bottom does have some very slight scratches.