The fastest autocross cars are purpose-built "specials" ("A Modified" in SCCA Solo) with small lightweight bodies, sticky tires, powerful engines, and short gears.
Here are 2 sides to the same coin. Both concepts are extreme lightweights, featuring intense lightening, chopped roof, windshield, and doors, no fenders, and hebmeuller style rear ends. Same idea, different execution. While their top speeds are typically limited by the VW gearing, their transient cornering capabilities far exceed those of other vehicles not expressly designed for this.
Autocross, also known as "Solo," or by simply "Slalom", are races around a closed track that features numerous turns. These VW Concepts were designed to compete in extreme Autocross races, specifically, in the gymkhanas. Gymkhanas are an even tighter slalom track than autocross, with numerous turns around cones. It loops back upon itself and looks like a mix between autocross and drifting. Fast times require a lot of sliding and the lightweight racers intend to dominate.
For the slaloms, the Widowmaker uses the age old Beetle platform although trained by years of track racing experience. It comes complete with beam adjusters and lowered spindles for the front end and re-tweaked rear torsion bars, koni shocks all around. Widowmaker has Large-diameter (205/40X18 front and 235/40x18 rear) BRM rims with Pirelli P-Zero "Trofeo" rubber.
HardHeb uses modified 5th-generation Volkswagen Golf Mcpherson strut suspension, front and rear. A custom-engineered space-frame tube chassis and rollbar ties them together. HardHeb wears Large-diameter (235/40X18 front and 255/35×20 rear) Porsche "Gas Burner" style rims with Yokohama Advan AO48 tires.
Both racers feature identical full-flow 2332cc Type 1 engines with dual CB Performance 48mm Fuel injectors. HardHeb displays a custom aluminum twin free-flow headers and exhaust systems while the Widowmaker uses a bright red tuned freeflow exaust and a stinger.
In each racer, a close ratio Volkswagen Type 1 Pro Street IRS transmission is rebuilt. The HardHeb mid-mounted design neccessitated that the ring and pinion be flipped.