Dear Car Talk:
I swear my old Jaguar had a parking brake that automatically set when I put the car in Park, and released when I took it out of Park.
This was very convenient, as I never had to remember to set or release it. And I never tried to drive away with the parking brake still on, which I have done a few times in my Audi A7 and my wife's Toyota Minivan. Why don't other cars have this feature? -- J.C.
They do, J.C.
We've driven a few cars that have that feature recently, including several Mercedes models. And it's easier to do than ever.
Traditionally, parking brakes were operated by cable. You'd either yank up on the lever between the seats, or you'd tighten the cable by pushing on a pedal with your left foot.
But cables weren't perfect. They'd stretch over time and go out of adjustment. They'd rust and even seize up if they weren't used regularly. Or they'd just snap.
Recently, most car makers have moved to electrically operated parking brakes. Instead of a cable, there's a small motor on each of the rear calipers. And when you push a button in the passenger compartment, the motor activates and voila! The parking brake is on.
This not only eliminates all of the problems with the old cables, but -- since all you need to operate your parking brake is a button -- it also frees up space in the passenger compartment, which can then be devoted to more important things, like USB outlets and cup holders.
It also makes it incredibly easy to create an automatic parking brake.
You simply program the parameters into the car's computer. For instance, you say "when the car is put into Park and the engine is shut off, engage the parking brake." And "when the car is put into Drive or Reverse from Park, and the doors are closed and the seat belt is on, release the parking brake."
That's essentially what the Mercedes system does, with a few extra safety protocols.
And it's hard to imagine a scenario where you'd need the parking brake to be off when the car was in Park. Or need it to be on when the car was in gear and you're trying to accelerate.
So I suspect you'll see more automatic parking brakes in the coming years. It makes a lot of sense.