All this said, He is looking for a plastic model. I did a bunch of searches on the Chiron (but not the R8 nor the Mclaren), and could not find a plastic kit model. He might be an enthusiast that wants these cars in his collection, but cannot find a manufacturer of them, hence his questions. My answer in this scenario.... wait till somebody makes one. I doubt that nobody hasn't made an R8 model yet though, it's been out for about 10 years or so. The Chiron is relatively new. But I'd rather have a Veyron . Of course, if I could afford a Veyron....

And if you're looking for a high quality model of an existing item, 3d printing really isn't the best medium anyways. Yes, there are some fantastic prints out there in high detail, but not in the way your asking. Those are going to be some really really fine details the printer would have to replicate, and I think was mentioned, SLA may be your only choice for that level of detail. I'm not too familiar with the processes, but I'm under the impression SLA suffers from weakness of parts on the small scale. Hinges would break, edges wouldn't look just right, etc.

If you're hardcore about making your own model from scratch.... well, it'll cost ya as mentioned. I could recommend sculpting the body parts out of foam yourself from drawings, and then 3d scanning it, and then having a skilled modeller touch it, but that's a lot of leg work, and then you'd still have to find the drawings. Or possibly maybe finding a 6d CNC machine and doing the hole thing out of blocks of plastic or aluminum. But I guess it falls back to just waiting for a production kit to come out.