Did a little crunching--included 2008, since that's the earliest season the site has car info for, the judges might have more detailed info than this noob
Mazda: 6 wins--
4 in Miatas: New England 2008, Goin-for-Broken 2009, Gavel-Tap 2010, Sears Pointless 2010; the last three were by Eyesore Racing
2 in RX7s: South 2008, South Fall 2009
BMW: 5 wins, all in E30s: South Spring 2009-10, Texas 2009, Arse-Freeze-Palooza 2009, Cain't Git Bayou 2010; Texas 2009 and Bayou 2010 were from Race Hard Race Ugly, the only other team to date with more than one outright victory since 2008. Hooray parity!
Honda/Acura: 3 wins in 3 different cars: Integra at Altamont 2008, Civic at New England 2009, CRX at American Irony 2010
Toyota: also 3 wins in 3 different cars: Supra at Detroit-ish 2008, Corolla at Texas 2008, Celica at Laissez les Crapheaps Roulez 2009
Nissan: 2 wins, basically in the same model: a 200SX at Lamest Day 2009, and a Sentra at Goin-for-Broken 2010
Ford: 2 wins in 2 cars, both at Gator-Rama: Mustang in 2009, Taurus SHO in 2010
The only outright win for ANY GM marque since 2008: Geo, the Metro-Gnome at Arse-Freeze-Palooza 2008
Volvo's only win: a V8-powered 244 at Buttonwillow Histrionics 2009
Saab's only win: a 900 Turbo at Southern Discomfort 2010