don't police cars have their engines tuned up than the regular version of the car?
This is a popular myth. In reality, police cars have so much weight on them from all their law enforcement equipment that tuning the engine still wouldn't make up for the extra weight. It'd also be cost prohibitive to put bigger engines in the cars, they'd have to be installed by third party garages because the manufacturer wouldn't ship them that way just for the police.
Also, double post. In case you missed my previous post, go back. It's got a lot of content.