Why do American cars roll forward after they’ve stopped?

27 comments

1. Automatics and the driver didn’t apply the parking brake.

2. This is a function of an automatic transmission, not of the car’s nation of origin.

   Manual transmissions will do the same unless you disengage the clutch. Most cars will move forward at idle engine speed.

   Edit: if you mean when the vehicle is not in gear, its still a function of a manual transmission. A vehicle will roll forward or backward, even if in park and shut off, if it has not yet reached the set of the [parking pawl](https://en.m.wikipedia.org/wiki/Parking_pawl) unless you also apply the parking brake, which most people do not do unless they are on a hill or in another precarious position.

3. What shows and movies have this?

4. … what are you talking about?

5. Automatic transmissions are much more common here. People only use parking brakes is they are on hilly terrain (if then). This means when you park and release the brake the car rolls a bit.

6. That’s just automatic transitions. Canadian ones do too

7. Yep, it’s the automatic transmission. Basically unless you’re braking you’re in first gear and the engine will move forward at ‘idle’ speed, basically 5mph/8kph. Some cars will hold the brake if you press hard, and release it when you touch the gas – it’s meant for bad traffic so you don’t have to hold the brake or put the car into park when stopped.

8. It’s a combination of automatic transmissions and people not using the parking brake.

   There’s a little rotation in the trans before the parking pawl locks up the transmission, so the car can scoot a little. If you set the parking brake, regardless of transmission type, that locks the wheels directly so there’s no movement as it settles.

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   It is telling that Americans often refer to this as an e-brake (emergency brake) rather than a parking brake. It’s just not used that way much at all outside of steeply hilly areas, the relatively few people driving manuals and extra cautious types.

9. When an automatic transmission is in drive it will roll forward regardless of what country it is in

10. Every car with an automatic transmission does that. Even the ones in your country.

11. It’s a ‘Murica thing. American cars have so much freedom in them that even after they are parked, they’re still champing at the bit to go onward!

12. Aside from the mechanical issue with automatic transition people already mentioned there’s also the fact that the white line you’re supposed to to stop at is usually a little too far back to properly see oncoming traffic in the street you’re hoping to cross or turn into… so many people will come to a complete stop at the line and then creep forward slowly to get a better view of traffic and/or prepare cross the intersection. Is this what you’re talking about?

13. It would seem from the comments that it is not the norm to apply the parking brake when parking in the states?

14. Do you mean the time it takes for an automatic trans to engage the trans brake? Which shouldn’t happen because people should be engaging the parking brake.

    Which sadly isn’t common, even though you should be doing it

15. Not an American but I know what it is. My grandpa doesn’t have leg and arm so he bought a car with automatic transmission and it drives forward without giving it gas ! Basically a car for disabled people

16. People don’t use the parking break

17. It’s a function of automatic transmission. It will roll slightly until the transmission engages. In America, people with automatic transmissions don’t generally use the parking brake, and the overwhelming majority of cars in the US have automatic transmissions. It’s not a national thing, particularly since the vast majority of newer vehicles in the US are using transmissions designed in Japan (JATCO) and Germany (ZF).

18. Idle moves the car when its in drive.

19. “As seen on tv!” count: 124.

20. Do you mean at a stoplight or actually parking the car?

21. Transmission

22. automatic transmissions

23. To keep you on your game

24. Because the car is an automatic that still in drive?

25. Even at low idle most cars will have enough power to be able to roll forward if you release the brakes and the car is in gear.

    That is it.

    American cars tend to have a lot of torque in the low RPM range but a German car will do the same.

    Electric cars have a ‘creep’ feature that mimics this because people are so used to releasing the brake and having the car inch forward.

26. Automatic and a really weird aversion to putting on the parking break

27. People generally don’t tend to use the parking brake. I taught myself almost thirty years ago to go from drive to neutral, engage parking brake then put car in park. I see people get in there cars, start it then when they shift from park to drive you can hear that loud clunk as the gears are grinding together. 😬