This is a huuuge improvement. The way I see it, it's not necessarily that your level of skill improved - it's just that you were hitting a mental block when it came time to apply your existing skills to cars, so you ended up approaching them differently from how you'd approached all the other kinds of vehicles.

This case, it's totally different. Your constructions feel really solid and well built out, and every feature you've added exists in a way that makes sense in 3D space. There are a couple places where proportions get a little messed up (mainly on the backside of the VW beetle) but all in all you've really knocked these out of the park.

I am very pleased to mark this lesson as complete, and with it, the entire course! Congratulations, and keep up the fantastic work.