Yes, those cars are definitely in a different class than a Z4, which is both good and bad. There is no warranty per se, but they are much simpler than a Z4, mechanically and electrically. They fall in the same category as building a street rod. You provide your own warranty service. I'm toying with the idea of getting involved in SCCA SOLO racing, and the idea of doing that with a brand new Z4...?
Cobra 5.0L - 225 hp, 9.5 lbs/hp, 0-60 4.7 sec.
Z4 - 225 hp, 13.3 lbs/hp
M3 - 333 hp, 10.2 lbs/hp, 0-60 4.8 sec.
Cobra Big block - 450+ hp, 5 lbs/hp, 0-60 3.75 sec.
The Cobra has been tested in excess of 1G cornering, Z4 & M3 are less than 1G.
Don't know, gotta think about this one, but I have several years until I am ready to buy. Or maybe I should get a used 328i or Z3 for SCCA use that will be usable across several classifications. Any suggestions from you guys involved in SCCA? I'm thinking about SOLO I Trials and Hill Climbs.