Well, it's gonna be fairly obvious that I'm going to disagree, but I think the best way to handle this is for me to spell out my thought processes on the different points.
First off, as you point out, "Superior vehicles are one of a kind and the price will reflect it." And I have to agree on that point; a car that runs better than others of its model, either due to superior upkeep, chance or any one of a number of possibilities will be worth more--often alot more. Afterall, there are alot of ways for a vehicle to run less efficiently ("ways" being a catchall term for arrangement of parts, maintenance and other factors) but comparatively fewer ways for a vehicle to be
more efficient than the manufactured baseline. Thus, such a vehicle will " cost more
and be harder to find (either on the lot or someone willing to sell)."
Thus, onto the meat of this post. First:
This Year's Hot Model.
I renamed it from "Popular" to better reflect what I think you were going for, although "Chop Shop Bread And Butter" could also be a possibility, alot like how late 90's Honda Civics are endangered because they're worth more as spare parts than as vehicles. But the idea that there are plenty of spare parts out there that would allow the owner to "Gain a black market pipeline for this particular vehicle for upgrades and repairs" was what I thought that you were going for, and, since spare parts have to come from
somewhere, I noted that there is an "increased chance that it might get stolen." And since it's "Popular" or an insurance nightmare (flip a coin) I gave it +
20%,
+3 Availability, to reflect those points, although I could see it being anywhere from a +5% to +20% instead of a flat +20%, depending on circumstances, which should be up to the GM.
Tuned.
Giving a vehicle significantly better performance (which a 20% boost to Speed or Acceleration is, most definitely) should cost more.
Alot more. Keep in mind that IRL, street racers can spend tens of thousands or more to wring out that last bit of performance, and since this doesn't take up any modification slots, that makes it extra valuable, which makes the +
20%,
+2 Availability feel downright generous, to be honest, as it's basically a free (slot-wise) Engine Customization. And, for comparison's sake, 5% of a Hyundai Shin-Hyung is only 850

, but getting an Engine Customization for that vehicle costs between 5000

and 8000
Fame.
This one's a tough one, but, thinking about it, I'll go with that it's "Like the quality". Therefore, the vehicle is possibly recognized on sight; how this is different from Pimped Ride? Well, then, that means that the vehicle is famous in its own right, and therefore has possible collector's value--meaning that those people who want a piece of memorabilia are probably going to jack up the price significantly.
+50%-200%+, +8 Availability, minimum.
Erased.
An unregistered--heck, an
actively unregistered--vehicle in the age of ubiquitous surveillance should be worth its weight in gold. Like the unregistered firearm of yore and lore, it might be a crappy POS, but the fact that Big Brother doesn't know about it and it
can't be traced to you makes it incredibly valuable for career criminals--and the fact that it's actively kept Erased by something means that it's all the more valuable. There's no way that this sort of vehicle can be worth less than double its normal price at the high end, which is why I went with +
50%-100%,
+4F/+8F Availability. Look at it this way; the availability modifiers in Core recommend a +50% price boost for "active law enforcement crackdown on item." This is just taking that into account.
Superior Design.
Heck, if I had a car that ran this smoothly, I'd be loath to part with it for anything less than a hefty surcharge! Alternatively, idiot-proofing is an expensive process and the corp has to make back its costs somehow. +
10%/25%/50%/100%:
+4/+8/+12/+16 Availability; The opposite of Gremlin. For each level of this quality the vehicle ignores dicerolls that would have created a glitch.
Greased Gears
As noted above, anything that gives a boost to speed or reaction time should be hard to get ahold of.
Fuel Efficient.
Take a look at modern electric or dual fuel cars. See how much of an "efficiency" surcharge people are willing to pay nowadays, and then tell me that
+10%/20%/30%/40%:
+1 Availability per level isn't fairly reasonable.
Slot Machine.
This one I'm not too sure about on my pricing, but at the same time, I'd rather err on the side of caution than allow for a potentially broken ability to get past me (and my usual litmus test for "broken" is "does my inner muchkin start jumping up and down, doing cartwheels and enumerating the things that I can do with it?" If "Yes" then "Broken"), hence the
+10%/20%/40%/60%: +1 Availability per levelAverage.
I'm not even sure why this one needs to be in here, but note that I actually
reduced the cost of this "quality", due to the definition of "average": if it's able to blend in with the herd, then it doesn't stand out in any way--which should include price.
+5%; no Availability change:
Standard Equipment.
This was outright broken, IMHO; getting a modification built in for only a 5% surcharge? So, free mod slots for a 5% surcharge? Yes, please, can I have another? Heck, I feel that even my tweak is still borderline broken; I'm tempted to change it to
+10% per free slot + mod cost, +2 Availability + half Availability of mod OR Availability of mod, whichever is higher. Also, I know enough about engineering design to know that squeezing something else into the design is hard enough as it is; if this is a one-off, instead of a production line item, or a short production run, that means that the the cost of engineering it in has to be offset by a much higher price.