Here are a few images from Cars: Mater-National mod.

Cars: Mater National Hi-Octane Edition Trailer

This video shows most of the available cars, a race in the original Tailfin Pass, the second Radiator Springs race from the original game and a Piston Cup track race.

Gameplay images and screenshots

Playable Count Spatula (all race modes) Playable Snot Rod (all race modes)
Playcspat Playsnot
Snot Rod alt skin Fillmore as new playable character in Tractor Tipping minigame
Playsnotnewskin Playfillmoretractor
New playable character from Cars, Sonny (all race modes) Playable Fletcher(All Race Modes)
Playsonny Playasfletcher
Playable Yuri(All Race Modes) Los Angeles Speedway beta (from Cars: The Videogame)
Playyuri Cars Mater 2014-09-07 07-34-16-07
Los Angeles Speedway (geometry/textures done) Los Angeles Speedway (geometry/textures done)
PistonLA1 PistonLA2
Tailfin Pass (original Cars version) Mater the Greater (WiP)
Tailfin classic Cars Mater 2014-09-25 19-59-57-46
Piston Cup Lightning Dragon Lightning McQueen
Cars Mater 2014-09-25 19-59-24-88 Cars Mater 2014-09-25 19-59-27-40
Beach Racer Lightning (WiP) Wide Body Lightning (WiP)
Cars Mater 2014-09-25 19-59-43-41 Cars Mater 2014-09-25 19-59-45-36
Matador Lightning (WiP) Off-road Lightning (WiP)
Cars Mater 2014-09-25 19-59-48-86 Cars Mater 2014-09-25 19-59-47-09
Tokyo Mater (WiP) El Materdor (WiP)
Cars Mater 2014-09-25 19-59-53-44 Cars Mater 2014-09-25 19-59-55-37