Issues...
1) Once you selected a part, you cannot unselect a part. You cnanot delete single parts, only click something else.
2) Why did it keep my design every time I started over, but ditched my engine? Keep the engine in place!
I never forgot to ADD a core, but I kept forgetting you took it out when all I was doing was changing a tire.
3) The solutions are preposterous and sometimes nonsensicle. The bridge one, I tried the solution in the walkthrough before looking at the walkthrough, but apparently I was like a hair off. The other one where you needed to dangle the long car in the air to hit the flag, also just about impossible to guess sans walkthrough.
4) The build area was too small for some of the solutions! When the solution calls for 2 long red cars, you wouldn't think it was allowed since two of them don't both fit inside the box. The build area should actually fit all the pieces needed.
Interesting game, but between the fustrating building techniques and the nonsensicle solutions, it was more trouble than it was worth and that took away from the enjoyability.