Hennessey is a Texas-based car manufacturer featured in Forza Motorsport 4 and all subsequent installments.
Headquartered in Houston, Texas and founded by John Hennessey, Hennessey Performance Engineering is an American tuning house specializing in modifying high-performance cars from brands like Chevrolet, Ford, Dodge, Jaguar, Lamborghini, and McLaren.
|“||The high-speed cravings John Hennessey drove the creation of Hennessey Performance back in 1991. It started with Hennessey’s daily-driven, a Mitsubishi 3000GT, that he drove in speed events such as the Nevada Open-Road races, Pike’s Peak Hill Climb, and a record-setting 174-mph run at the Bonneville Salt Flats. Hennessey turned his automotive passion into a successful business, originally focusing on turbocharged imports, until a customer inquired about modifying a Dodge Viper. The subsequent modifications to that Viper resulted in an average speed of 164 mph in the Silver State Challenge and drew attention from the likes of Jay Leno (along with Chrysler executives). Soon, Hennessey Venom 500 Vipers were flying out of the shop. The incredible performance of these cars led to modification packages for the Ford GT, Cadillac CTS-V, Chevy Camaro and, of course, the Hennessey Venom GT. The company’s goal is ultimate performance for its customers, no matter what vehicle they want to modify. Hennessey Performance is based outside Houston, Texas on 143 acres that include Lonestar Motorsports Park – a quarter mile drag strip and 1.4-mile racing circuit.||”|
— forzamotorsport.net 
|2012||Hennessey Venom GT||RWD||1200 hp (895 kW)||1155 ft·lb (1566 Nm)||2685 lb (1218 kg)||42%||6.2 L|
|United States Manufacturers|
|Acura · AMC · Baldwin · Buick · Cadillac · Chaparral · Chevrolet · Chrysler · Delorean · Devon · Dodge · Eagle · Eagle-Weslake · Ford · GMC · Hennessey · Hot Wheels · Hoonigan · Hudson · Hummer · Infiniti · Jeep · Lexus · Lincoln · Local Motors · Mercury · Mosler · Moses Smith Racing · Oldsmobile · Panoz · Plymouth · Pontiac · Ram · RJ Anderson · Robby Gordon · Rossion · Saleen · Saturn · Scion · Shelby · SSC · SRT · Tesla · Viper · Watson|