I went to
http://www.radiators-champ.com/RSRLiveTiming/ and compared the fastest times vs the Carrera S, which did a 1:38 at Brand GP.
Cars that around 1 second that I found were:
M4
F40 Stage 1 (weird combo
)
GT40 (again, weird combo)
Lotus Evora GTE Carbon
Lotus Exige 240R Stage 3
Lotus Exige V6 CUP (faster than Porsche)
Mazda MX5 CUP is a bit over a second slower, but closer than expected, still, won't be a match, but close.
Mazda RX7 TUNED, same as the MX5, slower but fairly close.
Porsche 911 Carrera RSR 3.0
Porsche Panamera Turbo
RUF CTR Yellowbird (probably bit too fast on a single lap)
Shelby Cobra
These were obviously all hotlap times, so not reliable for race distance. Saw quite a lot of cars around the 1:40 range and F40, GT40 and Shelby were actually quite close, but they were proven to be quite impopular.
Carrera vs M4 looks fun I think, maybe add 1 Lotus, but not sure where they really fit in a race.