You always have the transmission pawl as a backup when you park. I think the wide shoe would be important if you needed to use it as an emergency brake.

Modern cars have dual diagonal hydraulic circuits for the brakes. A sudden catastrophic failure of the braking system is nearly impossible, so I would not view the parking brake as an emergency brake - some new cars that have an electronic parking brake will not even allow you engage it while the vehicle is in motion, so it does not function as an emergency brake at all on those cars. Those two little drums are not going to slow the car from highway speed anyways, in an effective way. Additionally the parking pawl has been known to break off, and using it exclusively puts undue stress on transmission internals.

The correct way to park an automatic vehicle is to put the transmission into neutral, set the parking brake, remove your foot entirely from the brake pedal allowing the weight of the car to rest against the parking brake, and then lastly shift the transmission from neutral to park. This eliminates the stress from the parking pawl, and uses the parking brake as intended. The shoes performing as intended are therefore a rather important part of the system.

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1998 E300 turbodiesel

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