Most of us, if we're being honest, don't see a police car as a vehicle of hope, heroism or rescue. We see it as the reason we can't keep travelling at 88mph along the motorway, or as the bearer of potential bad news.
To find out the real story, autocar.co.uk's Steve Sutcliffe joined PCs Pendleton and Mawer, two of the Met Traffic Division's 640 officers, for an evening.
Gliding along the A40, Sutcliffe notes the reaction of other drivers as they see the police car. "You can pick the guilty from the innocent almost by their reactions alone," says Sutcliffe.
Constable Mawer pulls up alongside a tatty-looking burgundy Mitsubishi Galant at a roundabout. He reckons the front tyres look a bit thin, so he gives the chap a quick blast on the blue lights while Pendleton, in the passenger seat, indicates for the Mitsubishi to pull over.
A young lad gets out, looking utterly bewildered. Turns out he's on his way to work just up the road, and he's driving his boss's car. Unfortunately, though, it has almost no tread left in one of its front tyres, which means our friend will receive a £60 fine and get three points on his licence.
I ask PC Pendleton how fast I need to be driving on a dry, clear section of the M1 in order to get stopped. He says that as long as I'm not driving badly and that conditions are good, he personally wouldn't pull me unless I was doing more than 90mph. Which is nice to know.
Having said that, official Association of Chief Police Officers (ACPO) guidelines state that on the motorway (and assuming conditions are good), anything below 79mph and you're okay. From 79-95mph you'll get a ticket. Above 95mph you'll go to court and, very probably, face a ban.