You know what, I'm just going to do it, car cards. (I'm saving the tricks for a potential second series.)
I will be shopping the cards together based on text and preferably also a picture people provide. If you figure you know how to use a car, you can write the card. But first things first, I want input on the design to turn the current concept into something we can all agree on.
Here is my concept design:

The stuff I need input on (you can address as few or as many as you like):
Text: Is this the right amount of text? Are these the right categories/paragraphs? The idea is that every car will get its information shoved into the same categories, so they should work for every car. Are top speed and acceleration really important enough to list them like this? Are the titles of the categories okay? Is this a format in which you can convey how to drive a car, at least well enough that people can start practicing?
For easy reference, this is roughly the amount of text that fits into this format:
Top speed: 154/156mph
0-60/100: 2.9/5.6s
Properties: Fast, Custom, Short,
6-speed
Tips: The Superkart can take a large
corner at top speed. It is prone to
magic carpets. It is great for inside
loopcuts due to its small width. It can
be tempting to use automatic gears,
but the brakes are strong, shifting
down slows you down more precise.
Best use: Tracks with lots of corners
and few straights.
Properties: What are all the properties a car can have? Fast, Slow (both about cornering and feel, if the numbers for top speed and acceleration stay separate, maybe name them differently to clarify that?), Medium-Fast? (For cars like the F40 and LWT ZR1-GT3 maybe? Or just don't list them as either slow or fast?) Rigid Powergear, Flexible Powergear, Anti-Powergear, How do you call what the Speedgate has, First Gear Powergear?, Short, Long, 6-speed, Original, Custom, Wide?, What's a good word for not wide? anything else?
Text formatting: What do you think about the size, font (current font is Arial Nova Bold), distance between lines etc?
Colors: I'd like to stick to the Stunts ingame Palette, agreed? That would be these colors:

Outer line color: I'd like to do something with this. I was thinking, maybe have different colors for fast and slow and powergear cars? Something like that, so it reflects certain categories? Otherwise we could use one of the series of related colors to show a gradient, lighter=faster or something? Or just match it to the car's color? EDIT: Oh, oh, we could make it a difficulty rating, how hard is this car to master? It wouldn't be spelled out on the card, because that's discouraging, but there's still an automatic omnious vibe from a red or black card. Probably have 3 or 4 steps. Something straightforward like the Jaguar is easy, something like the Vette (poor cornering combined with rigid powergear, 6 gears) is hard.
Extra outer line: Should there be a "fake printed card" white border with rounded corners around the card? I'm leaning towards no.
Fill for text space: I don't like completely white, I do kind of like taking one color from the picture and letting it run through like this (it looks a little weird, but also kind of cool) but I'm certainly open to other suggestions and variations.
Picture: My idea is to have a single non-animated picture. A screenshot from outside the car, stretched from 320x200 to 640X480 (but oldschool pixelated stretching, no mixing colors), the way the game was meant to be viewed. There should not be a replay bar or dashboard in the picture. Minor modifications are allowed (I can do those) to remove things like the "replay" text or the mouse or to make details like Crashper's face above look better. The picture is best if the car, in its iconic primary paint scheme, looks really big in it (my example is a really small car the zoom doesn't go any closer), if the situation portrayed fits the car (the kart in a corner, the Lancia on dirt or ice, the Indy in a huge jump...) and bonus points for style if it's a picture from some sort of historic replay (the one above is from Renato Biker winning ZCT131, a race with almost all karts, on a track designed by the designer of the kart (a cool guy by the way, that designer)).
Method of distribution: I can just pack the pictures up as a combined zip, that would be the easiest option. But if anyone has any fancier ideas like a website or an actual trading game where you have to earn cards off of other pipsqueaks or earn one per race you join or something I'm listening.
Anything else? Major stuff I'm forgetting?
(The card above is an example, the information isn't super thought out yet. Advising against the automatic gear for instance is a bit of a mixed bag. But feedback is welcome if you have it...)