Are NASCAR vehicles "organically" related to the conventional models they are named for, or is the link arbitrary/marketing.

I do not know, what I do know though that in the superior DTM series, only the body shell is taken from the original models, the rest is a custom developed pure race car.

Let me put it this way… I have seen the vehicles close up !!
The headlights are actually painted on….. !!!

I think that a heavily modified version of the factory engine block is the only real factory part on there, and even then it’s often from another vehicle made by the same automaker. After all, you never see a rear-wheel-drive Toyota Camry with a carbureted V-8.

The frame is not stock. The race cars are tube-framed; that is not just a roll-cage welded into a factory unibody. The body is not the stock sheetmetal, and may actually vary slightly from factory specs, though not by much if they want to remain within the rules. We’ve already addressed the drivetrain. And I don’t think that any of the race cars use Macpherson struts, so that is also different.

All that is shared is the name. Current cars are all minor variations of the “Car of Tomorrow”, which bares no resemblance to the cars designed by the companies. The headlight stickers etc are designed to resemble the road car, but that is all they share. Even the engines have been standardised to allow all teams an even footing.

I think I asked this a year or two ago. Oops.

I think there are even templates that they use to inspect the cars for shape and stuff.

@majorrich You are correct; they do have templates to compare the body shape to that of the factory-stock car. IIRC, they are allowed to vary by no more than ½”.