I'm a fan of Car Wars, too. That was, iirc, the first game I got into that wasn't D&D. I was playing Car Wars before Shadowrun was even released! Lots of good times with that game... and I
still consider it the gold standard for vehicular combat games. Although, I've heard very interesting things about Gaslands... but alas I haven't had the opportunity to try it.
At any rate, Shadowrun has too much "theater of the mind" to make a Car Wars style vehicular combat system to integrate well. Heck, a Shadowrun combat round is 3 seconds... which is quite plausibly an entire Car Wars game where the time interval is 5 moves to the second (or 10 moves to the second, back in the 1e Car Wars days when I played!) I daresay the degree of granularity is incompatible between Shadowrun and Car Wars. Of course, for all Car Wars did well it didn't do 3 dimensional movement particularly well. Using planes/choppers in Car Wars was an absolute nightmare... imo the best aerial combat table-top game I ever played was Crimson Skies... but that essentially treated any differences in elevation between aircraft as being irrelevant and therefore climbing/descending was also irrelevant... and its initiative and damage systems would be basically impossible to make compatible with Shadowrun
One of the things I rather liked about 5e was treating car chases/combats with abstract values. How many meters per turn am I travelling? Largely doesn't matter. What does matter? whether the scene is a Speed or Handling environment, and your vehicle as a corresponding Limit. I also liked the 5e rule giving movement TYPES higher top speeds than anything below it... anything on wings is faster than anything with rotors, and anything with rotors is faster than anything on wheels, and anything on wheels is faster than anything on foot. Of course, this begins to have problems when you introduce superpowered shadowrunners who can more or less move at vehicular speeds INTO a vehicular scene, but nothing's perfect, right?
Of course, 6e is back to concrete speed and acceleration/braking values. Other than the fundamental difference in the size of time increments this is indeed Car Wars-esque, but only in a 1 dimensional sense. There's no discrete turning radii, so even a more or less one dimensional chase down a highway necessarily has GM fiat involved due to lateral motion involved in drifting across lanes and/or swerving to avoid obstacles.
Anyway. back on topic.
With regards to Crashes vs Rams: I'm personally ok with those being two different mechanics/damage calculations. While they both involve collisions, they're fundamentally different in the former is an accidental collision, and the latter is an intentional collision. You can reasonably maximize the damage to the target while minimizing the damage to yourself when you're colliding on purpose.
But is it necessarily THAT cut and dried? If I "ram" a building or a wall, is that truly any different than accidentally driving into it? To that I'd say "Maybe. It depends." 6e depends on GM discretion, and I'd say this is yet another example. If you drive nose-first into a solid barrier, I'd say it's a crash. Even if you meant to do it. OTOH, if you go to the bother of hitting it rear-end first or in some other way that would reasonably minimize the damage you suffer in the collision, I might call it a ram instead. Or, have you make a piloting test and if you pass it's a ram and if you fail it's a crash.
In the case of colliding with a moving target, I think the "did you do that intentionally" rule of thumb is pretty solid. But I agree that the damage should be calculated as a difference between the two, rather than solely on the ramming party's speed. Yes, as Car Wars would do. I think it's reasonable to infer that the calculation as written is presuming a stationary target for a ram, and in the event the target is NOT stationary you go ahead and use the relative speed.
