the premiums have three big outliers that will set blazingly fast times (the X1, F10 and F2007), while the standards have only one quick outlier (the FGT). the premiums also only have four monotonously slow cars (fiat 500F, kubelwagen, schwimmenwagen, samba bus), while the standards have far more (things like the beetle, kei cars and kei truck). the premiums have about 50 race cars in 200 cars, while the standards have about 150 race cars in 800 cars, so in the end I think the premiums would win for sure.
If 200 premiums and 200 hand picked standards did a lap, the standards would win quite comfortably.
On the other hand if 200 premiums and ALL standards did a lap the premiums would win comfortably, simply for the fact that all the MX5's, Miata's, Sirion's, Storia's, Pick-up trucks and other slow cars would drag the standards average way down.
The premiums, easily.
There's some slow stuff in the premium dealership. However, most of what you can get is actually pretty fast. The various NASCARs and SuperGT/JGTC cars will make for a nice average and the F10 and F2007 and especially the X2010 will push the average even further. Out of the 200 premium cars, 25% (or something) are race cars. Another 25% would probably be super cars like the Ferraris and Lambos. Then there's, like 35% of average cars (Skylines and the like) and maybe 15% of slow stuff (Miatas and what not).
On the standard side of things, I'd guess that 50% of the cars are slow stuff, 20% are average, 15% on super car levels and 15% race cars, roughly.
That'd probably be incredibly one sided in the premium cars' favor.