@baukepost Hey, nice job so far! You may have solved your problem by now, but just in case: In the “Introduction to Hard Surface Modeling” course (the cartoon airplane one) you are taught how to block the interior with simple shapes!

From your sketches, I think the seat should be more to the front, the steering wheel should be around the middle of the upper leg. I don’t know if the car is a 4 seats-two doors type, but if it is, there’s no space to get in!