Alrighty! So, across many of these, I'm quite pleased with your results. There are a number of issues here and there in individual constructions, but it largely comes down to mistakes in keeping all the different structures straight in your head, which itself can be a really demanding task considering just how complex it all gets. I will point them out of course, but all in all you've done some pretty great work here.

To start, despite your concerns your form intersections are largely well done. Just look out for the issues marked out here. The most notable one is that the intersection between the box and the sphere in the bottom right doesn't actually follow the curvature of the sphere.

Moving on, your cylinders in boxes are generally well done - although this is a technique that could have helped issues such as the wheels in your formula 1 racer. You noted yourself that you used the wrong vanishing point for those minor axes, but I'm uncertain as to which vanishing point you actually used, since their rotation in space actually has them angling inwards, oriented towards none of the major vanishing points in the scene shared by anything else.

That aside, with this drawing I did notice that you had a fair bit of divergence with the spoiler, and other aspects of the construction as shown here appeared to try to stay completely parallel instead of converging towards some far off vanishing point. Maintaining your awareness of lines actually converging - even if very gradually - is critical to making a drawing feel believable.

When it comes to civergence, similar issues are visible with this construction. Once the initial box had been constructed though, I think you did a pretty good job of adhering to it, and largely minimized the impact of that initial box being skewed.

Aside from those early experiments, I definitely feel like your non-car vehicle drawings generally came out very well. The tank and boat demonstrations, as well as this military vehicle came out quite nicely. I'm especially pleased with how those wheels came out, and the overall construction definitely felt quite solid. The only shortcoming I'd mention are some of the smaller details like the headlights and the other elements along that front area. These appeared to be drawn a little more flatly. It can definitely be tricky when dealing with such small forms, and often it can be a better strategy to treat them more like texture, maintaining their three dimensional nature by implying them through small cast shadows rather than blocking in shapes that make them feel like they don't protrude or dip into the surface onto which they're being appended.

Now it is fair to say that your greatest difficulty did lie with your cars. It's true that cars are notoriously difficult, and impose a lot of additional challenges, but their sheer complexity can also exacerbate existing problems by making us feel more overwhelmed, and by causing us to rush through certain decisions (given that car drawings can often take many, many hours to tackle, taking even as long as your most patient tank can actually be rushing depending on the car that's being drawn).

As you can see here, a key problem is that along the top section of your car, you've started converging your lines more rapidly, aiming them towards an imaginary vanishing point that no longer sits along the horizon line. This causes severe distortion along the windshield, stretching it out, and causing the car to become quite lopsided. As far as the hood/grill/headlights/front wheel/etc. are concerned, they're all very well drawn, but it's really important that you always look at other existing lines in the construction to always remind yourself of roughly where your vanishing point is actually meant to sit. Keeping an eye on the horizon line can also help with this.

This kind of lopsidedness comes up fairly frequently - in your tesla truck for instance, the far left side of the windshield ends up being far larger than the far right side.

I think throughout the other kinds of constructions, you do demonstrate your ability to be patient, to think through all your perspective problems and to keep things consistent, but the sheer imposing nature of cars with all of their complexities appears to overwhelm you and causes you to fall back to old habits. As such, before I mark this lesson as complete, I'm going to assign two additional car drawings.

Take your time. I really mean it when I say these things can take hours - one of the best cars I've seen from a student took the student upwards of 6 hours, if I remember correctly. And you don't need to be doing this all at once - take frequent breaks, and allow your brain to relax. You can even (and probably should) span a single drawing over the course of several days, and be sure to make full use of a ruler to identify your convergences before committing to a line.

Of the two extra car drawings, I'd like one to be a Ford Model T (one of the old ones from the early 1900s), and the other to be a sports car. With the second one especially, you may want to do some preliminary blocky constructions just to identify where your vanishing points should sit in relation to the car to avoid distortion.