For two seasons Jaguar / TWR campaigned modified Group C cars in the hugely competitive IMSA GTP Championship and not without success. The ever increasing performance of the rivalling Nissan and Toyota-Eagle teams nevertheless called for the development of a purpose-built IMSA racer for the 1991 season. In anticipation of the new XJR-16, Jaguar raced the old XJR-10 for the first two short races of the season and even scored atWest Palm Beach.
Mechanically, the XJR-16 leaned heavily on its predecessors although there were several major modifications. The aluminium honeycomb reinforced carbon fibre monocoque remained virtually unchanged. The rear half of the car had been subject of most changes. The bell-housing had been lengthened to give the car a longer wheelbase. The suspension was also completely revised and now featured push-rod actuated dampers and springs that were mounted on top of the gearbox. All of the previous TWR Jaguars had featured springs mounted next to the uprights.
Not having to worry about Group C's fuel consumption limitations, the designers of IMSA GTP could just pile on wings and simply stop for fuel more often. This led to ever increasing levels of downforce on these full ground-effects racing cars. TWR's answer was the introduction of a two-tier rear wing, which made its IMSA debut on the XJR-16. While this created incredible levels downforce and very efficiently, it did gave the car a rear aerodynamic bias. This was addressed during the season with some creativity.
