# Car question \[What is "overdrive"?\] **URL:** \ **Category:** Factual Questions\ **Created:** [August 2, 2023, 5:35pm UTC](https://boards.straightdope.com/t/car-question-what-is-overdrive/987970 "2023-08-02T17:35:53Z")\ **Posts on this page:** 12\ **Page:** 3
**Author:** ![Johnny\_L.A](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/johnny_l.a/32/1084_2.png) [@Johnny\_L.A](https://boards.straightdope.com/u/Johnny_L.A)\ **Post date:** [August 4, 2023, 6:20pm UTC](https://boards.straightdope.com/t/car-question-what-is-overdrive/987970/41 "2023-08-04T18:20:17Z")
> [@Chefguy](#): > > On cars with automatic transmissions, it engages automatically at highway speeds. I think my Jeep Cherokee’s shifter has 1-2-3/4, where ‘¾’ is third gear and overdrive. I’ve seen other automatic transmission indicators that have an O within a circle to indicate overdrive. > [@mixdenny](#): > > My Triumph TR3 has a Laycock De Normanville overdrive, So does my '66 MGB. It works in 3rd and 4th gears. ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [August 4, 2023, 6:31pm UTC](https://boards.straightdope.com/t/car-question-what-is-overdrive/987970/42 "2023-08-04T18:31:01Z")
My dream car was once an Austin Healy 3000 Mark III with overdrive. I could have purchased one for a few hundred bucks in the 70s if I had a few hundred bucks in the 70s. I could get one now if I had an extra 50 grand to spend. ‘Overdrive’ made it extra cool, even though I didn’t know what it was it had to be something better than not having it. ---
**Author:** ![Dr.Strangelove](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr.strangelove/32/6613_2.png) [@Dr.Strangelove](https://boards.straightdope.com/u/Dr.Strangelove)\ **Post date:** [August 4, 2023, 10:31pm UTC](https://boards.straightdope.com/t/car-question-what-is-overdrive/987970/43 "2023-08-04T22:31:11Z")
> [@LSLGuy](#): > > All of this is mostly obsolete nowadays when stripper Toyotas come with manually shiftable 7 speed auto-transmissions. Not to mention EVs. The idea of figuring out _which_ part of the car to heat up from the downhill potential energy conversion is rather quaint. And sorta offensive if I can’t get back that energy I paid good money for. Long downhills are a beautiful thing in an EV. Not only do you not think at all about overheating the brakes or overrevving the engine, but it’s like putting gas back in the tank. ---
**Author:** ![Philliam](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/philliam/32/3011_2.png) [@Philliam](https://boards.straightdope.com/u/Philliam)\ **Post date:** [August 6, 2023, 4:26pm UTC](https://boards.straightdope.com/t/car-question-what-is-overdrive/987970/44 "2023-08-06T16:26:33Z")
My Dad always referred to a siphon hose as an “Oklahoma Credit Card”. ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [August 6, 2023, 4:42pm UTC](https://boards.straightdope.com/t/car-question-what-is-overdrive/987970/45 "2023-08-06T16:42:41Z")
Along with a ragged overloaded paper shopping bag AKA “Kentucky luggage”. ---
**Author:** ![bob\_2](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bob_2/32/3341_2.png) [@bob\_2](https://boards.straightdope.com/u/bob_2)\ **Post date:** [August 7, 2023, 8:46am UTC](https://boards.straightdope.com/t/car-question-what-is-overdrive/987970/46 "2023-08-07T08:46:02Z")
> [@LSLGuy](#): > > Going downhill on a long steep grade the transmission will also tend to end up in top gear. My Ford Mondeo (Fusion in the USA) will automatically change down on downhills if cruise control is engaged. ---
**Author:** ![control-z](https://avatars.discourse-cdn.com/v4/letter/c/eada6e/32.png) [@control-z](https://boards.straightdope.com/u/control-z)\ **Post date:** [August 8, 2023, 7:20pm UTC](https://boards.straightdope.com/t/car-question-what-is-overdrive/987970/47 "2023-08-08T19:20:05Z")
I had a 1978 MGB with an overdrive switch on the gearshift. I treated it like a sort of 5th gear. There was some sort of dire warning that you weren’t supposed to leave the overdrive engaged when you went into reverse, but I forgot and did so many times with no apparent problems. ---
**Author:** ![snfaulkner](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/snfaulkner/32/433_2.png) [@snfaulkner](https://boards.straightdope.com/u/snfaulkner)\ **Post date:** [August 10, 2023, 12:44pm UTC](https://boards.straightdope.com/t/car-question-what-is-overdrive/987970/48 "2023-08-10T12:44:12Z")
Oh great, do you know many kings I’ve had to rememorize?! Stop messing with time! ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [August 10, 2023, 1:31pm UTC](https://boards.straightdope.com/t/car-question-what-is-overdrive/987970/49 "2023-08-10T13:31:03Z")
…Was that meant for some other thread? ---
**Author:** ![Johnny\_L.A](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/johnny_l.a/32/1084_2.png) [@Johnny\_L.A](https://boards.straightdope.com/u/Johnny_L.A)\ **Post date:** [August 10, 2023, 2:12pm UTC](https://boards.straightdope.com/t/car-question-what-is-overdrive/987970/50 "2023-08-10T14:12:02Z")
> [@control-z](#): > > There was some sort of dire warning that you weren’t supposed to leave the overdrive engaged when you went into reverse, but I forgot and did so many times with no apparent problems. I had a '77 MGB with the [switch on the shift knob](https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcQZ7g1H_z78HbsE9MKrdmQnLL36ID6DsLAG5Q&usqp=CAU). The overdrive on my '66 is engaged via a [switch on the dash](https://barnfinds.com/wp-content/uploads/2015/02/1966-MGB-Laycock-Overdrive.jpg). Overdrive is only engaged in 3rd and 4th gears. I was driving a year or two ago when a driver in front of me forced me to quickly downshift into 2nd, where I had to stay for a minute while I silently cursed the guy. When I shifted back into 3rd, the engine bogged down. Since I have a problem with vapour lock, I thought that’s what was happening. It turned out that it was just a big step from 2nd to overdrive-3rd. Since it’s SOP is to disengage overdrive before shifting down from 3rd, I don’t see how it would be engaged in Reverse. ---
**Author:** ![control-z](https://avatars.discourse-cdn.com/v4/letter/c/eada6e/32.png) [@control-z](https://boards.straightdope.com/u/control-z)\ **Post date:** [August 10, 2023, 2:24pm UTC](https://boards.straightdope.com/t/car-question-what-is-overdrive/987970/51 "2023-08-10T14:24:38Z")
I never quite understood the reason for not having overdrive engaged in reverse, but discussions like this were confusing enough that I tried to avoid it: [Engaging reverse gear with overdrive switched on : MGB & GT Forum : The MG Experience](https://www.mgexp.com/forum/mgb-and-gt-forum.1/engaging-reverse-gear-with-overdrive.3979666/) It sounds like perhaps you need to reverse pretty fast (15MPH+?) and some sort of failsafe fails before damage happens. ---
**Author:** ![Pushkin](https://avatars.discourse-cdn.com/v4/letter/p/ee59a6/32.png) [@Pushkin](https://boards.straightdope.com/u/Pushkin)\ **Post date:** [August 18, 2023, 10:30am UTC](https://boards.straightdope.com/t/car-question-what-is-overdrive/987970/52 "2023-08-18T10:30:44Z")
> [@pulykamell](#): > > I remember it mostly from 90s-ish automatic gearboxes. Some had the Overdrive button on the shifter – I feel like some also had it elsewhere, like on the gear shift console. Here’s an example of one (not my picture): The last car I saw one in where it was probably an actual separate unit was my father’s late 80s 740, operated with a switch on top of the gear lever. [Previous page](https://boards.straightdope.com/t/car-question-what-is-overdrive/987970.md?page=2)