 The exhaust system is equipped with two catalytic converters , which reduced the power output of the engine . During testing at the <unk> Ring in Italy the XJ220 , driven by 1990 Le Mans Winner Martin Brundle could achieve a top speed of 217 @.@ 1 miles per hour when these catalytic converters were removed and the rev limiter was increased to <unk> ; owing to the circular nature of the track , a speed of 217 mph ( 349 km / h ) is equivalent to 223 mph ( 359 km / h ) on a straight , level road . The V64V engine had the additional benefit of being very economical for such a powerful petrol engine , it was capable of achieving 32 mpg @-@ imp ( 8 @.@ 8 L / 100 km ; 27 mpg @-@ US ) , in contrast , the smallest @-@ engined Jaguar saloon of the time , the Jaguar <unk> 4 @.@ 0 could only achieve around 24 mpg @-@ imp ( 12 L / 100 km ; 20 mpg @-@ US ) . 
