This was a question I was offhandedly asked the other day, by a young person just learning to drive.
I said most likely, depending on how many HP the car’s engine had, it would rev really high, then lurch forward, eventually burning the brake pads.
“Huh,” she said; “I was hoping it might take a screenshot or something.”
I am pretty sure she was joking, and yes it struck me that one probably has to be 21 years old or younger to think of that as a natural outcome (it took me, a 53 year old man, a few seconds to even get why she would say that).
But - was I right? Other friends of mine I’ve told this to, said “no, the brakes are way stronger than the engine in modern production cars, you’d just kill the transmission.”
But I feel like this has to be something where “it depends” on the engine torque, the brakes (disc or drum?), the weight of the car, … right?
Because I’ve never done this (obviously), but I have driven my car with the parking brake engaged, down a steep mountain pass with the brakes under constant stress (even aided by engine braking), and with my two rear brakes mostly seized (but not quite fully).
On pretty much anything short of a drag racer, the brakes would win. The car won’t move and since there’s no movement of the brake disks they won’t heat up dramatically. An automatic transmission would eventually suffer, a manual transmission may simply stall out.
She probably was joking, but have you seen the instructions for doing various real things with a car computer? Often, just to reset the clock or something, you have to turn the ignition on and off five times, wait three seconds, and then press the AC and radio buttons at the same time, or some stupid thing like that.
I would imagine that the type of transmission installed in the car would be the biggest factor in this.
First, are you in neutral? If so then nothing would happen save revving the engine to the redline regardless of transmission type.
If a standard manual transmission, and you’re in gear and not depressing the clutch, naturally you’d immediately stall the engine. If you have the clutch depressed (and have 3 feet) then the engine would revv up just as if you were in neutral.
An automatic in decent working order? You’d likelly get some increased RPM’s but it wouldn’t revv up to the red line thanks to the drag caused by the torque converter. What exactly would happen I confess I’m not sure as the condition of the torque converter and transmission itself would play a part.
Assuming your brakes work as designed then they wouldn’t wear or get hot as there isn’t any friction because nothing is moving at the wheel.
That was going to be my (joking) answer. So the line comes from somewhere. Maybe it was originally about a Tesla, since they are pretty high tech, but somebody (a comedian?) has made the joke that if you press the gas and brake at the same time, the car takes a screenshot.
Tests following reports of people unable to stop their cars because the gas pedal was stuck down have shown repeatedly that brakes will stop the car from moving. If someone couldn’t stop their car they weren’t stepping on the brake.
I don’t know if something like a Tesla in ludicrous mode could out drive the brakes though. I don’t recall any look at that.
The OP doesn’t say “press both pedals to the floor from a standing start”. They just say “press both pedals to the floor”.
I agree with the folks upthread as to the standing start case. Brakes win, car sits there, and the engine stalls or revs to redline or above until it fails or you get off the gas.
But the situation is more nuanced if you’re cruising down an uncrowded freeway at e.g. 60mph and floor both pedals from that situation.
IMO …
The engine and transmission on a powerful car may be slightly less powerful than the brakes, but the brakes have a finite lifetime before they heat and fade, whereas the engine/trans can pull at full power for a much longer time.
On a wimpy econobox good bet the brakes will outlast the engine/tranny. Perhaps not so on a real rocketship of a car.
Mt Bronco has a “flat-foot-crank” for priming the lubrication system after an oil change:
After changing the filter, replacing the drain plug, and filling the engine with fresh oil, you can prime the engine WITHOUT starting it - do the “Flat Foot Crank”:
Press and hold both the brake and gas pedal all the way to the floor.
Press start button - engine will crank as long as you hold it down, but will NOT start. 5-10 seconds should be plenty to prime the engine.
Release start button, release both pedals. Press Start button again to start engine normally.
I think the dumbasses called it power braking where they open the hood on a car and step on the brake and gas at the same time to watch the engine jump. I’m not sure what damage this can cause aside from weaking the motor mounts but it just seem like a stupid idea in general.
We had a similar thread a while ago that talked about two-footed driving. The risk with using both feet to drive (specifically, a modern automatic transmission equipped car which I note for the aggravating pedants with nothing useful to add but who insist that the answer account for the peculiarities of the 1892 Humbert Foldabout) is that someone will stomp on both pedals at some point, so a lot of the same issues were discussed.
This is a critical factor. From a stop, stomping on both pedals will allow the brakes to win an easy victory. The car stays stopped, the engine revs and the transmission eventually gets hot. If you did that until the gas ran out, maybe the transmission would overheat and fail first. But the car won’t go anywhere.
In some powerful rear-wheel-drive cars, the rear wheels might spin in place having overcome the resistance of the weaker rear brakes but the stopped front wheels will keep the car generally stopped. The back end might wiggle a bit but the car won’t generally go anywhere until you let up on the brakes. See “brake stand” videos on Youtube.
But, if the car is already moving at speed and you stomp on both pedals (front, rear, or all wheel drive), the brakes may heat up a lot before the car comes to a stop. They may even overheat and become useless while the engine is still racing, generally rendering the car uncontrollable. See my post on the litigation surrounding Ford’s defective cruise control systems, which created exactly the situation of a car moving at highway speeds where the throttle seemingly opened all the way and the driver was left stomping on the brakes to stop it. The short version is that stopping the car was theoretically possible from 5 mph but perhaps not by a weaker driver who couldn’t generate 175 pounds of pedal pressure. The test didn’t start at 75 mph and I suspect the brakes would have failed before the car ever stopped from that speed.
Finally though, modern electronics come to the rescue. Lots of modern cars (but much less than all) will cut the engine power automatically if both the gas and brake are stomped on at the same time and so the car will just come to a sudden stop. No drama at all and nothing broken.
That’s the default mode for most EVs, but even so, the traditional brake remains usable in case you’ve misjudged the distance needed for stopping or need to brake in an emergency situation. The one-pedal driving modes provide relatively gentle regenerative braking that just matches most normal braking needs.
In cars with a “launch control” mode, your fastest off the mark acceleration involves exactly what the OP describes: pressing the brake and throttle fully. I’ve done it in my Audi S3. Instructions:
Then you just release the brake and the car launches.
I was the OP in that thread, and I put it specifically in GQ because I wanted factual comments, not opinions. I led off with a Vox article that indicated that there was no evidence that two-footed driving was a risk.
Despite my request to keep it factual, the rest of the thread was anecdotes and opinions. My recollection is that nothing was posted that undercut the conclusion in the Vox article.
The torque converter stall speed will come into play, not allowing engine RPM’s to go above a certain point till movement is made. So no it’s not going to redline.
That only applies if the wheels are turning, from a stop, no heat, no fade.
Next time the student is in the car, give it a go. Find a secluded spot, off the public way and with plenty of open pavement. Mash & hold the brakes and give the throttle a few spikes, not to too long. The car will shake and roar but not roll.
Of course. Which was the context that line was made in: an already-moving car. I had already discussed the stationary car scenario in the earlier part of that post.