In spite of winning both the World Championship and the Le Mans 24 hours in 1998 Jaguarsport, a collaboration between Tom Walkinshaw's TWR and Jaguar, decided that there was little potential for development left in the large and heavy production based V12 engine and so started development of a V6 turbo for 1989.
This was particularly needed for the shorter races that made up the American IMSA Championship where they were up against the powerful Nissans and Toyotas. The much smaller and lighter, 143Kg against 240Kg, all aluminium JRV-6 enabled Tony Southgate and Ross Brawn to pen a slimmer carbon monocoque for the XJR-10 allowing better aerodynamics in a tighter package.
On the XJR-10’s debut at the Lime Rock round of the IMSA Championship Jan Lammers qualified 389 on the front row and went on to finish in 2nd place only 8 seconds behind the winner, a tremendous result in such a competitive series. Shortly afterwards 389, again driven by Lammers along with Price Cobb, was victorious at Portland.
For the remainder of the 1989 IMSA season 389 was raced by Lammers, paired with Cobb in the longer races, picking up 2 victories and 3 podiums. Davy Jones also racing it once in the 2 hour race at San Antonio. These results giving Jaguar second in the 1989 IMSA Championship.
In 1990 the Jaguar XJR-10s finished runners-up again in the IMSA Championship, 386, crewed by Cobb and John Nielsen, taking another victory at Lime Rock before Martin Brundle took the helm for the final race of the season at Del Mar. That was also the final race for the Jaguars in their Castrol livery.
For 1991 the Jaguars were presented in “Bud Light” colours, this was to be the year of the XJR-16 but it was not ready at the start of the season so 389 was wheeled out for Raul Boesel to use in the sprint races at West Palm Beach and Miami which Boesel won, a fitting swansong.
Altogether the XJR-10 scored 6 outright victories in the IMSA Championship with chassis 389 taking 4 of them making it by far the most successful Jaguar.