Well I finally decided to drop 10 Europeians on this, from everything Wizard's been posting my initial thoughts are that it looks to be something along the lines of a GT5 / iRacing combo hybrid (perhaps with a bit of GRID thrown in, loved the demo of that but never got the game).
Seems like it's got a mix of the sim elements of iRacing with the cars and motorsport variety of GT5, I've yet to find a full car list yet but I've been shuffling through some of the news posts and have found some awesome cars / motorsport classes to be included:
FORD1966 Mustang 2+2 fastback (foundation trade dress for 1966 Shelby GT350)
1967 Ford MK IV
1972 Escort RS1600
1980 Capri (Group 5 – Team Zakspeed)
1988 Sierra RS500 Cosworth (Group A)
1997 Mustang Cobra (SCCA Trans-Am)
2012 Fusion NASCAR Stock Car
2012 Focus ST
2012 Focus ST (BTCC)
2013 Falcon FG (Australian V8 Supercar Car of the Future)
2013 Ford Shelby GT500
BMW2012 1M
1978 320 Turbo Group 5
1999 V12 LMR
2012 BTCC 3-series
1981 BMW M1 Procar
1991 BMW M3 Group A Touring Car
1940 328 Touring Coupe
2008 F1.08
2012 Z4 GT3
2012 BMW M3 E92 GT
GinettaGinetta G40 Junior
Ginetta G50
Ginetta G55 GT3
Classic Lotus Race Cars1962 Lotus 25 (Formula One car)
1965 Lotus 40 (open-top sports car)
1965 Lotus 38 (Indy 500 winner)
1967 Lotus 49 & 1970 Lotus 49C (Formula One car)
1967 Lotus 51 (Formula Ford car)
1968 Lotus 56 (Indy Car)
1970 Lotus 72 (Formula One car)
1977 Lotus 78 (Formula One car)
1986 Lotus 98T (Formula One car)
PaganiZonda R
Cinque
Huayra
CaterhamCaterham Classic
Caterham R500 Superlight
Caterham SP/300.R
And others too that I didn't list, so there's BTCC, DTM, Rally, LMP, Historic and Modern F1, SCCA, some form of Nascar / Stock car type stuff, various open wheel cars and more. Dunno how many of those are already included in the test builds yet (only seen Wizard in a Stock Car, Caterham and Audi DTM car I think) but that's still looking to be a pretty impressive vehicle selection!
Even with a slightly less complex tire physics model on the consoles this is definitely looking like it'll be a competitor for the likes of GT and Forza, hopefully the folks at PD are taking note of developments like this (and their consumer base) and will make GT6 into an equally good game as this is shaping up to be.
I wish this download would hurry up, still got about 2.5Gb to go!