Actually most 'pursuit' cars are Volvo T5R Estates (Wagons) or BMW 525tds - and the drivers got into a habit of using the PIT when it wasnt necessary to do so when there were units up the road with stingers, and as a consequence, they'd write off the cars, or cause £1000's of damage to the car, and they billed the taxpayer for something like 8million quids worth of repairs and written off vehicles, and the govt went ballistic and ordered the police federation to change their regulations with regards to PIT's.
They can only be done when given the direct order to do so by a regional commissioner, at which point its HIS arse on the line.
Similar things apply for the armed units SO10 and SO19 (SpecOps), if they shoot someone dead, theres no 'in the line of duty' crap, they actually have to go through murder trial proceedings. Of course, 99% of the time its justified and under orders, but it still hampers efforts to bring the out of control situation in this country under control once more (like it was in the 80's under the iron fist of the conservative govt).