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Every automatic transmission car I've driven (not sure if all do this) allow you to shift from Reverse to Neutral and from Neutral to Drive (and therefore Reverse all the way to Drive) without pressing the brake or hitting the little shift lock on the gear selector. However, it doesn't let you go the opposite direction from Drive to Reverse, or Reverse to Park, etc.

According to this question if you don't stop completely before shifting its possible to damage your transmission. Some cars apparently mitigate this damage but it still seems strange to even allow the opportunity.

So why would car designers give you the feature to shift from reverse to drive without hitting the brake of it can cause damage? Even if it didn't cause damage why would they not allow you to shift in the reverse order without braking?

Please note I'm not asking how this is done, I'm asking why it is like this.

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I don't have reference for this, but believe the reason for the positive lockout going from drive to reverse is so you don't accidentally shift from drive to reverse while at speed. Can you imagine going 60 mph down the road and dropping it from drive into reverse? You can expect catastrophic consequences for your transmission if you were to do this. If there weren't a positive lock to bring it out of drive going to reverse, how easy would it be for you to accidentally move the shift lever (considering a floor shift lever) from drive if it wasn't in place. Also consider driving down the road at that speed and punching it up into reverse. You would not only be putting your own life in danger, you'd be putting everyone around in you danger with the very real possibility of a wreck in the process.

My belief is that you can go from reverse to drive without stopping is for convenience sake. It is very likely you can damage the transmission by not stopping the vehicle between reverse to drive shifting (we used to call this a neutral drop in days of yore). The difference here is the speed at which you are moving when going in reverse is not that great. You most likely are not going to accidentally move the shift lever down from reverse into drive. I'm not saying it won't happen, but even if you did, the damage would not be as instantaneous as it would be going in the opposite direction. There is also a lot less possibility of a wreck at those speeds, so that is a consideration as well.

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  • In many if not most cars reverse is locked out if the forward speed is too high. You can shift it into reverse all you want but the transmission will not actually do the shifting.
    – vini_i
    Commented Sep 9, 2015 at 0:02
  • I remember magazine articles in the '70s about a test of a new pre-production gearbox where the driver went to move from economy to sport and hit reverse instead at high speed. The test driver was killed. So, yes, it is a safety feature.
    – Chenmunka
    Commented Sep 9, 2015 at 8:53
  • Anectode: a fellow student from my university days had a 2002 Mitsubishi Magna who used to ward off tailgaters by flashing the reverse lights on and off at highway speeds. He claimed to do this by rapidly cycling between "N" and "R". Not that I recommend anyone try this.
    – Zaid
    Commented Sep 29, 2015 at 18:13
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The answer is simpler then you might think. You are allowed to pull the gear shifter into neutral regardless of where it is pulled from to disengage the transmission. This is for safety, to be able to stop a runaway car regardless of if it's in drive or reverse.

The ability to pull the car into drive from neutral comes form the occasional need to limp a car along when it's having engine troubles. The engine can only be started in in park or neutral. When your in neutral you can still be rolling along and trying to start and engine. When the engine starts then the shifter can be smoothly pulled into gear.

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