# Can I Drive My Cadillac CTS at 80 MPH-In Reverse? **URL:** \ **Category:** Factual Questions\ **Created:** [May 17, 2012, 10:46am UTC](https://boards.straightdope.com/t/can-i-drive-my-cadillac-cts-at-80-mph-in-reverse/622195 "2012-05-17T10:46:09Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![ralph124c](https://avatars.discourse-cdn.com/v4/letter/r/8797f3/32.png) [@ralph124c](https://boards.straightdope.com/u/ralph124c)\ **Post date:** [May 17, 2012, 10:46am UTC](https://boards.straightdope.com/t/can-i-drive-my-cadillac-cts-at-80-mph-in-reverse/622195/1 "2012-05-17T10:46:09Z")
I saw the new Cadillac CTS ad on TV-impressive car! The ad shows two cars side by side, traveling at high speed-one in reverse. I didn’t see the standard disclaimer “Don’t try this at home”-does this mean I can do this? ---
**Author:** ![Nunzio\_Tavulari](https://avatars.discourse-cdn.com/v4/letter/n/b9bd4f/32.png) [@Nunzio\_Tavulari](https://boards.straightdope.com/u/Nunzio_Tavulari)\ **Post date:** [May 17, 2012, 11:08am UTC](https://boards.straightdope.com/t/can-i-drive-my-cadillac-cts-at-80-mph-in-reverse/622195/2 "2012-05-17T11:08:40Z")
> [@ralph124c](#): > > I saw the new Cadillac CTS ad on TV-impressive car! The ad shows two cars side by side, traveling at high speed-one in reverse. > I didn’t see the standard disclaimer “Don’t try this at home”-does this mean I can do this? You could, but the gearing in reverse may prevent you from reaching 80mph. I expect that you can do 60. You can’t do it for too many miles though. The cooling system depends on air coming in through and below the grill. The airflow going over the exhaust tips will impede the exhaust and may superheat the catalytic converters. You’ll effectively have rear wheel steering which is very difficult to control above walking speed. They may not have said “don’t try this at home” but they also didn’t say that you can do it for a longer period of time than is depicted in each individual shot. Make sure that you put it on You Tube. ---
**Author:** ![kayaker](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kayaker/32/441_2.png) [@kayaker](https://boards.straightdope.com/u/kayaker)\ **Post date:** [May 17, 2012, 11:19am UTC](https://boards.straightdope.com/t/can-i-drive-my-cadillac-cts-at-80-mph-in-reverse/622195/3 "2012-05-17T11:19:51Z")
YouTube? He’ll, rig a live feed. ---
**Author:** ![Rick](https://avatars.discourse-cdn.com/v4/letter/r/9f8e36/32.png) [@Rick](https://boards.straightdope.com/u/Rick)\ **Post date:** [May 17, 2012, 11:23am UTC](https://boards.straightdope.com/t/can-i-drive-my-cadillac-cts-at-80-mph-in-reverse/622195/4 "2012-05-17T11:23:05Z")
Reverse is usually geared about the same as 1st gear which on most automatics is good for maybe 30MPH tops. ---
**Author:** ![Hail\_Ants](https://avatars.discourse-cdn.com/v4/letter/h/dc4da7/32.png) [@Hail\_Ants](https://boards.straightdope.com/u/Hail_Ants)\ **Post date:** [May 17, 2012, 12:45pm UTC](https://boards.straightdope.com/t/can-i-drive-my-cadillac-cts-at-80-mph-in-reverse/622195/5 "2012-05-17T12:45:55Z")
Just to be clear, what everyone is saying refers to a _physical impossibility_, not some computer or mechanical lock-out that will _prevent it_ from occurring. IOW because reverse is such a low ratio gear the engine could not achieve a high enough RPM to propel the vehicle at such a high speed as 80mph. Here’s some fun: Cadillac CTS: 5L40-E model transmission has a 3.20:1 reverse gear, a 3.40:1 final drive, engine redline around 6,000 rpm, and 285/35-19 size rear tires. Sooooo… [ul] [li]6000 engine max rpm ÷ 3.20 reverse gear ratio ÷ 3.40 differential ratio = 551 rpm rear wheel max rotation in reverse[/li][li]A 285/35-19 tire = (35% of 285mm = 100mm = 3.9" × 2 = 7.8") + 19" rim = 26.8" total wheel diameter × π (3.14) = 84.1" total wheel circumference[/li][li]84.1" × 551rpm ≈ 46,400 inches per min × 60 = 2,748,000 inches per hour ÷ 12 = 232,000 feet per hour ÷ 5280 ≈ **44 MPH _approximate top speed in reverse!_** [/li][/ul] There are slightly different engine top speeds, transmission types, tires sizes etc. available, but none that will change that figure significantly. Certainly not double it… ---
**Author:** ![Rick](https://avatars.discourse-cdn.com/v4/letter/r/9f8e36/32.png) [@Rick](https://boards.straightdope.com/u/Rick)\ **Post date:** [May 17, 2012, 1:07pm UTC](https://boards.straightdope.com/t/can-i-drive-my-cadillac-cts-at-80-mph-in-reverse/622195/6 "2012-05-17T13:07:36Z")
Your math is wrong. The wheel diameter is not the rolling diameter of the tire. the tire is larger than the wheel. So if anything you number is low. ---
**Author:** ![xenophon41](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/xenophon41/32/253_2.png) [@xenophon41](https://boards.straightdope.com/u/xenophon41)\ **Post date:** [May 17, 2012, 1:18pm UTC](https://boards.straightdope.com/t/can-i-drive-my-cadillac-cts-at-80-mph-in-reverse/622195/7 "2012-05-17T13:18:53Z")
> [@Rick](#): > > Your math is wrong. The wheel diameter is not the rolling diameter of the tire. the tire is larger than the wheel. > So if anything you number is low. What are you disagreeing with? The additional 7.8" in diameter **Hail Ants** added beyond the rim to account for the tire, or the 19" diameter of the rim, or some other aspect of the 26.8" rolling diameter produced by that math? ---
**Author:** ![twickster](https://avatars.discourse-cdn.com/v4/letter/t/ec9cab/32.png) [@twickster](https://boards.straightdope.com/u/twickster)\ **Post date:** [May 17, 2012, 1:20pm UTC](https://boards.straightdope.com/t/can-i-drive-my-cadillac-cts-at-80-mph-in-reverse/622195/8 "2012-05-17T13:20:04Z")
Moved Cafe Society --\> GQ. ---
**Author:** ![DMark](https://avatars.discourse-cdn.com/v4/letter/d/e68b1a/32.png) [@DMark](https://boards.straightdope.com/u/DMark)\ **Post date:** [May 17, 2012, 4:11pm UTC](https://boards.straightdope.com/t/can-i-drive-my-cadillac-cts-at-80-mph-in-reverse/622195/9 "2012-05-17T16:11:57Z")
Can I Drive My Cadillac CTS at 80 MPH-In Reverse? Well, yes - once. ---
**Author:** ![kanicbird](https://avatars.discourse-cdn.com/v4/letter/k/5f8ce5/32.png) [@kanicbird](https://boards.straightdope.com/u/kanicbird)\ **Post date:** [May 17, 2012, 4:58pm UTC](https://boards.straightdope.com/t/can-i-drive-my-cadillac-cts-at-80-mph-in-reverse/622195/10 "2012-05-17T16:58:27Z")
Perhaps it could be done with a CVT (continuously? variable transmission) car ---
**Author:** ![Nunzio\_Tavulari](https://avatars.discourse-cdn.com/v4/letter/n/b9bd4f/32.png) [@Nunzio\_Tavulari](https://boards.straightdope.com/u/Nunzio_Tavulari)\ **Post date:** [May 17, 2012, 6:20pm UTC](https://boards.straightdope.com/t/can-i-drive-my-cadillac-cts-at-80-mph-in-reverse/622195/11 "2012-05-17T18:20:42Z")
> [@DMark](#): > > Can I Drive My Cadillac CTS at 80 MPH-In Reverse? > > Well, yes - once. For about twenty minutes ---
**Author:** ![Rick](https://avatars.discourse-cdn.com/v4/letter/r/9f8e36/32.png) [@Rick](https://boards.straightdope.com/u/Rick)\ **Post date:** [May 17, 2012, 7:04pm UTC](https://boards.straightdope.com/t/can-i-drive-my-cadillac-cts-at-80-mph-in-reverse/622195/12 "2012-05-17T19:04:16Z")
> [@xenophon41](#): > > What are you disagreeing with? The additional 7.8" in diameter **Hail Ants** added beyond the rim to account for the tire, or the 19" diameter of the rim, or some other aspect of the 26.8" rolling diameter produced by that math? My bad I skimed his response and saw 19" and pi. (when come back bring) ---
**Author:** ![Rick](https://avatars.discourse-cdn.com/v4/letter/r/9f8e36/32.png) [@Rick](https://boards.straightdope.com/u/Rick)\ **Post date:** [May 17, 2012, 8:15pm UTC](https://boards.straightdope.com/t/can-i-drive-my-cadillac-cts-at-80-mph-in-reverse/622195/13 "2012-05-17T20:15:07Z")
> [@kanicbird](#): > > Perhaps it could be done with a CVT (continuously? variable transmission) car With a DAF you can go as fast backwards as forwards.\* The only problem is that they won’t hit 80 in either direction. - car has a CVT with pulleys. ---
**Author:** ![Hairy\_Bob](https://avatars.discourse-cdn.com/v4/letter/h/ecc23a/32.png) [@Hairy\_Bob](https://boards.straightdope.com/u/Hairy_Bob)\ **Post date:** [May 17, 2012, 10:54pm UTC](https://boards.straightdope.com/t/can-i-drive-my-cadillac-cts-at-80-mph-in-reverse/622195/14 "2012-05-17T22:54:33Z")
Fifth Gear (UK channel 5’s answer to BBC’s Top Gear) did a segment on driving fast in reverse, which can be seen here [- YouTube](http://www.youtube.com/watch?v=sXcxamtLzbY) . In conclusion, the presenter mentions the figure 35mph, which I assumed is the flat out reverse speed of the diesel Primera used. I can imagine that a performance car might well be capable of up to 50mph in reverse, but any more seems highly unlikely. Why would they bother to make the gear ratio that high? Who wants to travel backwards at highway speeds, facing the wrong way and with the steering wheels at the wrong end? kanicbird’s comment about cvts got me thinking. I’m not aware of how the reverse gear is arranged in cvt cars, or even if there is a single “right” way. In tractors, though, in which cvts (or varios, as they are commonly known) are increasingly popular, one gearbox varies the gear ratio, while a separate gearbox handles the direction, so a wide range of reverse speeds is available, often up to the top speed on low speed machinery. If a similar arrangement were used in a cvt car then it could theoretically reach it’s top speed in reverse, although you still have the problem of overheating the engine due to lack of cooling air. Cars are simply not designed to run in reverse for long periods or distances, it is only intended as a maneuvering gear. ---
**Author:** ![GreasyJack](https://avatars.discourse-cdn.com/v4/letter/g/df705f/32.png) [@GreasyJack](https://boards.straightdope.com/u/GreasyJack)\ **Post date:** [May 17, 2012, 11:41pm UTC](https://boards.straightdope.com/t/can-i-drive-my-cadillac-cts-at-80-mph-in-reverse/622195/15 "2012-05-17T23:41:17Z")
There was an old car talk puzzler where this guy with an old Saab 92 challenges his muscle car driving neighbor to a reverse drag race… The 2-stroke engine in the Saab will run backwards, so when the race starts, he gets rolling backwards, shuts the engine off, shifts into first and then turns it back on. Now he has 1 forward gear and 3 reverse gears and so the Saab can rocket all the way up to its top speed of 55 (or whatever) while the muscle car hits its redline at 30. ---
**Author:** ![RandomLetters](https://avatars.discourse-cdn.com/v4/letter/r/8edcca/32.png) [@RandomLetters](https://boards.straightdope.com/u/RandomLetters)\ **Post date:** [May 18, 2012, 10:13am UTC](https://boards.straightdope.com/t/can-i-drive-my-cadillac-cts-at-80-mph-in-reverse/622195/16 "2012-05-18T10:13:08Z")
Car and Driver did a [Rental Car Olympics](http://www.youtube.com/watch?v=qe-F4KEKyvQ) video which includes both a reverse race and a Cadillac CTS as one of the cars. ---
**Author:** ![Loach](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/loach/32/350_2.png) [@Loach](https://boards.straightdope.com/u/Loach)\ **Post date:** [May 18, 2012, 11:28am UTC](https://boards.straightdope.com/t/can-i-drive-my-cadillac-cts-at-80-mph-in-reverse/622195/17 "2012-05-18T11:28:43Z")
There is nothing in that commercial that says the video wasn’t sped up to make it appear they are going faster. ---
**Author:** ![kayaker](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kayaker/32/441_2.png) [@kayaker](https://boards.straightdope.com/u/kayaker)\ **Post date:** [May 18, 2012, 11:47am UTC](https://boards.straightdope.com/t/can-i-drive-my-cadillac-cts-at-80-mph-in-reverse/622195/18 "2012-05-18T11:47:18Z")
> [@Hairy\_Bob](#): > > kanicbird’s comment about cvts got me thinking. I’m not aware of how the reverse gear is arranged in cvt cars, or even if there is a single “right” way. In tractors, though, in which cvts (or varios, as they are commonly known) are increasingly popular, one gearbox varies the gear ratio, while a separate gearbox handles the direction, so a wide range of reverse speeds is available, often up to the top speed on low speed machinery. If a similar arrangement were used in a cvt car then it could theoretically reach it’s top speed in reverse, although you still have the problem of overheating the engine due to lack of cooling air. > Cars are simply not designed to run in reverse for long periods or distances, it is only intended as a maneuvering gear. You’re telling me! I have a Jeep Patriot with CVT. Last night out of curiosity, and with access to a large, empty parking lot, I gave fast backward driving a shot. So, it was very difficult. Seemed more than a little dangerous. Attempting to drive backwards in a straight line as fast as I could go resulted in a crazy serpentine at maybe 15 mph. ---
**Author:** ![Dewey\_Finn](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dewey_finn/32/4222_2.png) [@Dewey\_Finn](https://boards.straightdope.com/u/Dewey_Finn)\ **Post date:** [May 18, 2012, 1:06pm UTC](https://boards.straightdope.com/t/can-i-drive-my-cadillac-cts-at-80-mph-in-reverse/622195/19 "2012-05-18T13:06:05Z")
> [@ralph124c](#): > > I didn’t see the standard disclaimer “Don’t try this at home”-does this mean I can do this? First of all, just because _you_ didn’t see the disclaimer doesn’t mean it wasn’t there. [Because it was, in fact, there.](http://www.youtube.com/watch?v=UDOy0MbnZmE) Second, do you watch movies and try all of the stunts shown because they don’t have disclaimers not to try these stunts at home? Third, where did you get the idea that the cars were being driven at 80MPH? The commercial certainly doesn’t say that. So in summary. You didn’t see something that was in the commercial (the disclaimer) but heard something that wasn’t (the speed of the cars). Try watching television more carefully next time. ---
**Author:** ![Crafter\_Man](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/crafter_man/32/458_2.png) [@Crafter\_Man](https://boards.straightdope.com/u/Crafter_Man)\ **Post date:** [May 18, 2012, 1:26pm UTC](https://boards.straightdope.com/t/can-i-drive-my-cadillac-cts-at-80-mph-in-reverse/622195/20 "2012-05-18T13:26:57Z")
In 1930, a couple guys drove from New York to Los Angeles - and back - in reverse: > **[N.Y. to L.A. and back -- in reverse](https://www.latimes.com/archives/la-xpm-2006-sep-28-me-a2anniversary28-story.html)** > > Sept. 28, 1930: After 42 days on the road, James B. > **[U.S. Census Bureau Daily Feature for July 23](https://www.prnewswire.com/news-releases/us-census-bureau-daily-feature-for-july-23-126048698.html)** > > /PRNewswire-USNewswire/ -- Following is the daily "Profile America" feature from the U.S. Census Bureau: (Logo:... [Next page](https://boards.straightdope.com/t/can-i-drive-my-cadillac-cts-at-80-mph-in-reverse/622195.md?page=2)