Not sure I fully understand this statement, but I’ll try to break it down.
By my rough count, there are around 130 American manufacturer cars in Forza 6 to date including disc and DLC. That’s about 25% of the 540+cars in FM6 to date.
That’s basically counting cars made by AMC, Buick, Cadillac, Chevrolet, Chrysler, Dodge, Ford, GMC, HUMMER, Jeep, Local Motors, Mercury, Oldsmobile, Plymouth, Pontiac, Ram, Saleen, Shelby, SRT, Tesla (including some Fords made in UK or Australia, which aren’t technically American made). There are also a lot of foreign manufacturers whose cars may technically be built in the states for the US market, but I’m not counting them. If you want to get really technical, a lot of American cars are now made in Mexico or Canada, but that’s a different topic entirely…
Depending on how rigid your definition of muscle car is, there are between 60-65 of them: around 40 are classic muscle (60s-70s), 8 or 9 from the muscle revival era like irocs and GNX (80s-90s), and around 15 or so modern muscle (2000+) like modern Mustangs, Camaros, Challengers Chargers - not counting modern Corvettes, Vipers, and Caddy’s which aren’t technically “muscle” in FM, even if a lot of people think of them as modern muscle.
So 130ish American cars total, almost exactly half of those are muscle (counting all eras), the other half non-muscle.
Maybe not as much as you want to see (by all means, add them to the car wish list!), but I’m not sure “barely any muscle cars” or “American non muscle cars is almost non existent” is an accurate statement of the Forza 6 car list once you do some digging.
If you’re specifically referring to DLC only, then forgive my ramblings…yes, it’s been fairly light on American & Muscle so far.