Has a crash car ever been used as intended by crashing into a cop so others can get away?
I've never heard of it happening but I think it must have worked at some point.
I also think that if someone did crash into a cop he woul be in a shit load of trouble with the law

Not as much trouble as a murder charge, come on use your head...

I think I first read about them in a book on Al Capone. Maybe they were common in Chicago back I the old days.

That’s a good question. I’ve never heard of a crash car actually crashing into a cop car. However, that’s not the only method. A crash car can simply block a cops path on a narrow road. A couple seconds delay can make all the difference if you have a good escape route.