Sounds like 2 cents.
It isn't hard to drop a motor in a tube frame chassis and achieve great straight line numbers by a favorable power/weight.
This isn't expensive to do, nor complicated, not in the slightest. Guys are making similar frames in their garages for their project 7s, etc. all the time. So are kids in college, namely SAE cars.
One is a kit car, with virtually no interior, crude fit and finish, no amenities, no "real body", no warranty, that doesn't have to pass government crash testing, etc. One is a production car, built to a much higher standard, with a much greater content, and that must pass emissions/crash testing.
About the ONLY thing you can compare on a production car (i.e. Vette, etc.) and an 818 is performance. In all other categories, there is no comparison, you're getting more in the production car, and you're paying for it. It is not unreasonable to compare its performance to much more expensive cars, they are much more expensive for reasons unrelated to performance.
Hence, FFR can make an 1800 lb. two seater, while a "real" car manufacturer would be hard-pressed to create a car that light without resorting to exotic materials, and $texas in R&D, with a sticker price of god knows what.