In August 2003 and with driver Pat Kinne at the helm, the car on display was the world's fastest estate car when it reached 225.609 mph (360.9 km/h) at the 55th annual Bonneville Speed Week Nationals which took place on the Salt Flats in Utah, USA. It returned in 2007 and again in 2008 and recorded 226.139 mph.
The MG ZT was based on the Rover 75 saloon car but incorporated trim and bodywork modifications to embrace a sporty image, along with uprated brakes and suspension and an emphasis on engine power. Estate models became ZT-T.
In 2002, MG Rover approached the California-based custom car specialists So-Cal Speed Shop to build a speed record car, Codenamed X-15, using the then forthcoming MG ZT-T V8 estate car as a basis. One of the purposes of the build was to celebrate the long Bonneville history of MG and market both the Rover V8 and MG brands.Roush Performance were chosen to build the bespoke engine; a 6-litre V8 with a NASCAR bottom end and a Le Mans Prototype Class 1 top end. It has electronic fuel injection with an output of 800 bhp without the aid of a turbocharger. Two parachute packs fixed at the back of the car assist when braking at high speed.