Tracks almost doesn't need any work with physics, gadgets, animations, moving parts, sound. Also because they are greater scale precision is less demanding. I still wouldn't do any real important track without LiDAR ever again. Because you'll work your ass off trying to make it precise, and people will still just don't give a damn about it, because it will not have the scan label, and spoilage is real. Unless it is some novelty so precision is less desired.
Track will be more difficult the larger it is and the more variety is there. For example if your track is running through one type of environment it will be easier than it would be if the surroundings of road is constantly changing very much. More objects around also means it will be more work. The more work you'll be able to do with as few splines as you can the easier it should be.
Tracks requires more consistency of your work quality. If you'll mess up at beginning you'll have more pain than you would with a car, unless you'd rush really far into progress with a car... it should still be easier to tweak things out IMO than for a messed up things at the track. I have experienced both. Though some modders here would remodel whole car if they mess up, rather than tweak it out...
If you'd do car, then try learning photo matching early. Most blueprints usually are off. Otherwise you'll see the pictures of a car when you'll be closing your eyes. And possibly go insane. But you'll understand the curves well
Well if you will understand them for once haha car can look totally perfectly modeled from one angle, and completely off from different angle.
For a car I would also look for less curvy car, with not too complex interior, also would check if it is symmetrical, for example I have been modeling D-Type not long ago, comparing to XJ13 and E-Type it is very asymmetrical, obviously it makes it a bit more difficult.
