We use Volvo's and Vauxhall's a lot in Britain.
The Vauxhall Astra is a work car, where as the Volvo is more special unit. The Ford Focus is sometimes seen as well. We even had Vectra's once as Police Car's. And even the iconic Mini got it's chance!
The G/B (above) is kinda what people think off when we say British Police Car.
The H/C (above) is a updated model and looks a little less bland.
The Volvo (below), as far as I know is in a estate form when used by police.
Jag's were and are being reconsidered as police car's.