A button like cruise control that keeps your car at the speed limit automatically
Posted by LULWbush@reddit | CrazyIdeas | View on Reddit | 111 comments
Tons of cars now have the speed limit dashboard display, this should be easy to do realistically
terriblesubreddit@reddit
It’s called intelligent speed assist, it’s been around long enough that it’s required on all cars sold in Europe
https://en.wikipedia.org/wiki/Intelligent_speed_assistance
Dizzy_Key_7400@reddit
Already a thing in the EU / UK. Modern Kias do it, you just change the settings to add a limit for the car from whatever the road is then put cruise control on. Probably similar in other cars too.
Problem is when GPS fucks up or the camera reads the wrong sign etc. where I live there’s a 1 mile stretch of motorway that is the UK 70 limit. GPS thinks it’s 40.
Dirty_Power@reddit
My Audi does this but it’s not great and will pick up on exit ramp speed limit signs and suddenly drop you down to 60km/h in the left lane, really incredible dangerous
feel-the-avocado@reddit
My toyota does this. If i hold the cruise control stick it sets it's speed to the road limit. It keeps track of any speed signs you pass and shows the current limit on the dash board all the time
Resident-Variation21@reddit
What Toyota? I almost bought a RAV4 but didn’t in the end. If it had this feature and I missed it I’ll be sad.
Rambo_sledge@reddit
My yaris hybrid does. Rav4 certainly does. The feature is called DRCC/RSA.
(Dynamic radar cruise control / Road sign Assist)
RandomUsername2579@reddit
Already exists
thetrivialstuff@reddit
I have a rental car right now that does this. It's not 100% flawless, but the user interface for it is the best that I've seen for this kind of thing yet -
It has a speed limit display on the console that looks like a speed limit sign, and just below that it shows what the cruise control is currently set to. If cruise is active, that number is green; if it's inactive, the number is white and has a little "paused" symbol next to it.
When the auto speed limit sign reader sees a new sign, this little arrow shows up with a question mark between the sign display and the cruise control number, with "OK?" If you click the "ok" button on the steering wheel, it'll copy the current speed limit into the cruise control. It keeps the current cruise state though, so if you had it paused, the car won't immediately accelerate.
If you double-click the "ok", it will both copy the number and turn on the cruise control and accelerate or brake to the new speed.
I really like it, because it's incredibly easy to set the new speed, but any change in speed always needs that little manual approval step. So the 1% of the time where the sign reader or the GPS gets confused and sees a completely bonkers speed limit, it has no effect, and at any time whether cruise is on or off you just want to tell the car "go the speed limit now!" there's a really fast way to do it.
Quirky-Flight-9812@reddit
One of the cruise control modes in my F-150 does this too. Will not go above the speed limit on the little speed limit sign on the dash.
ianuilliam@reddit
On my Mach E there's an option in the car settings to set tolerance for the adaptive cruise. If you set it to +9, for example, the cruise control will maintain 9 over the speed limit. I would think the f150 would have the same options, since they are both Ford.
Available-Wasabi-252@reddit
Its almost identical in my 2019 BMW.
FaxCelestis@reddit
What brand is this?
Additional-Simple248@reddit
Toyota does something like this as well.
thetrivialstuff@reddit
It's an Alfa Romeo EV. Model is a 2024 "Junior" I think?
I wouldn't recommend the car in general though, because it's got some design issues:
Tommie59@reddit
Sounds like Opel/vauxhall. I have this in my Opel van.
TechSupportAnswers@reddit
Extremely rare modern car that actually improves the experience
OkDrag3967@reddit
True. It’s should be easy to accomplish. It’s just that every now and then, my car will read 85 mph from a street sign instead of 35.
Laughing_Orange@reddit
Mine sometimes reads 200km/h in a 30km/h. No idea where the 2 or the second 0 came from. A 200km/h sign doesn't even exist within my country.
Artegris@reddit
Maybe it is fallback when it cannot recognize number on the sign, it sets no limit, which is 200 for some reason.
cabronfavarito@reddit
What country would a 200km/h exist in? That is insanely fast and most cars have trouble crossing 160
TDot-26@reddit
Almost every car from this century can hit 160kph eventually, where do you live?
cabronfavarito@reddit
Read over my sentence slowly dawg…
TDot-26@reddit
You said "most cars have trouble crossing 160"
Every car I've ever driven can cross 160
The_Troyminator@reddit
I’ve crossed 160 KM/hr in many cars before.
Hugo28Boss@reddit
160kph signs?
The_Troyminator@reddit
Lots of cars can go over 160 KPH. I had a 71 Delta 88 that could and modern cars can handle it even easier. It had a top speed of about 225, but I never brought mine that high.
Distinct_Rope@reddit
Lots of modern vehicles have a limiter around the 160km/hr range.
Every thing I've owned except the VW GTI was limited..
Extreme_Design6936@reddit
What cars are limited to 160kph? Genuine question. My 2014 nissan sentra will do nearly 200kph already.
Distinct_Rope@reddit
I don't have a comprehensive list, Google would be better for that.
Chrysler Intrepid, Lincoln Town car, Honda CRV, Ford Ranger, probably my Ford Fiesta though I haven't tried as it's probably power limited.
GTI was the only one that let me crack 200. Everything else clearly hits a limiter as it's not out of gear & was still accelerating when it clearly pulls power to a limit.
The_Troyminator@reddit
And lots don’t, depending on where you live.
kurai-tsuki@reddit
What? Even with our highest speed limit in the US being ~130kph, I don't think you could buy a car for sale today that can't exceed 160 (100mph)
cabronfavarito@reddit
Well for starters, America isn’t the only country in the world. Secondly I never said they can’t I just said they struggle to get there. If you have enough road then sure. My HRV can get to 160 with enough road but struggles to hit 170, the most I got it to was 182 or something.
My Nissan struggles to hit 160. Most I got it to was 165 I think, the car started shaking alot. My old Honda accord was the same story. I’ve driven plenty of cars, they don’t just hit 160 comfortably. You need a lot of road. I’m not getting into all the semantics
kurai-tsuki@reddit
I didn't say anything about America being special, I said that 160 isn't a difficult speed to reach, even when the speed limit isn't anywhere near that high. Maybe if you're in some 1L diesel it'll struggle but even a ten year old, low power Honda Jazz can reach 180 in ~25 seconds
Fa1nted_for_real@reddit
200km/h is almost certainly the maximum it will swt, so anything over that (say, 300) gets set back to 200kmh
Magic_mousie@reddit
Exactly this. My car claims to be able to do it already but I've kept it turned off. It's read 20 in a 40, it's read 80 in a 60 - we don't even have 80 as a speed limit.
Nice idea in practice, I'd love to not worry about speed cameras. But as it stands, the technology would give me a ticket, or worse, kill someone.
7-Inches@reddit
Google states that the speed limit of one road in Coventry is 80mph. There is never a situation in the UK where it is over 70
realityinflux@reddit
Seriously, mine picks up school zone limits as well as truck limits. But maybe if cars got a little smarter it would work. I suppose it wouldn't be prudent for them to set cruise to limit+14?
MrPogoUK@reddit
Yeah, my car’s constantly getting the limit wrong. I live on a 20mph road, which leads to a 30 and then a 60. On the way out it almost always misses the 30 sign and thinks it’s still 20, then when heading home almost always misses the 30 and thinks I’m still in a 60.
Ok_Two_2604@reddit
Mine gets it from the gps’ map. Still wrong sometimes.
NUMBerONEisFIRST@reddit
I can set mine to stay a car distance from the car in front of me no matter the speed, with a maximum speed set.
I set it to 60 and if the person in front of me slows down so do I.
HandbagHawker@reddit
speed limit data from built in nav systems like tomtom are horribly inaccurate.
spekky1234@reddit
Because you're not supposed to stay at the speedlimit all the time, that's just the upper limit for the road you're on. Oh look a sign indicating a sharp turn. Lemme stay in 80. Ice? But officer, i followed the speed limit, not my fault the ice yeeted me into this child.
Scrangdorber@reddit
My car (2022 Tesla model 3) has this, but for some reason it mostly doesn't do it. Like it reads the speed limit fine but ignores it... Except sometimes when it obeys it.
deskpro256@reddit
That would only work if the road rules everywhere use a speed limit sign on every road crossing. In our country a crossroad can mean the speed limit changes. In a city there can be a sign 30 and in the next major crossing its no longer valid and it is back to 50. Same on the highways. You could have a part of the road where there is a need to slow down the traffic and there is a sign 70, then when the road crossing has passed it it automatically back to 90. Now we would need signs on every road crossing because some folks can't drive.
Spirta@reddit
All I need is one of those sensors that automatically adjusts my speed to match the car in front of me so I don't have to slow down myself.
uncertain_expert@reddit
My Skoda is a mild-hybrid that is optimised to coast with the engine off when you lift your foot off the accelerator. In this mode it will slow automatically to be right at the speed limit if it changes lower whilst coasting down hill. Once past the sign though it will relax the automatic brake and the car will speed up again as it continues coasting down the hill…
Polymath6301@reddit
It’s a terrible idea (but it shouldn’t be). Why? Because the car manufacturers will set it to go what your speedo say is 100, but the car itself knows is 96 (which it will report via the trip computer).
It can’t do a true 100, because your speedo will report 104 (say) and you’ll think it’s broken.
Demand truth in speedos!
Fiskenfest-II@reddit
This was already a thing years ago?
igotshadowbaned@reddit
You've never seen a vandalized speed limit sign? One paint line and you've got cars zipping up from 35 to 85 mph
Juliet-November@reddit
The only thing I've driven with this used GPS maps rather than reading the signs.
schlaminator@reddit
Mine reads signs, but doesn't automatically change speed outside of the ACC setting. But, when I'm going for example 50 and the the car reads the next sign with say 120, all I have to do is hold ↑ for half a second on the steering wheel to set the ACC to the allowed speed the car read on the sign. Same for reduction. After 120, it's let's say 80, I hold ↓ for half a second, the car cruises the speed to 80. Short pressing the arrows only changes the ACC setting in increments of 5 (the first press rounds it to the next 5).
paulstelian97@reddit
My BMW automatically configured Cruise Control to target the speed limit when we were traveling in Austria, but never in any of the other countries we have been through (RO-BG-GR-SRB-HR-Slovenia-Austria-HU — only in Austria did it do it)
Your crazy idea is already implemented in certain regions on some cars.
Available-Wasabi-252@reddit
In Hungary you have to OK all limit changes, correct.
Ratfor@reddit
The problem then becomes who is responsible (or more importantly, Liable) for keeping the program up to date.
UsernameChallenged@reddit
I think my wife's Hyundai does that. If you set the adaptive cruise control to the speed limit (which it can tell from the signs), it gives a ding and turns green. I believe it then adjusts every time you see a new speed limit sign.
So I believe it exists, but might not be widespread.
Casiquire@reddit
Isn't it dangerous for a car to unexpectedly speed up beneath you?
100_Duck-sized_Ducks@reddit
There should be a setting where it only slows down if the limit drops and not the speeding up part
TheGT1030MasterRace@reddit
With laser cruise, no. If laser cruise is set to a higher speed than the vehicle in front of you is moving, it will just keep cruising at the speed of the vehicle in front of you, and leave an appropriate gap.
gheiminfantry@reddit
That's a very odd way of putting it.
paulstelian97@reddit
Dad didn’t like it when the cruise control automatically went down and back up when we were traveling in Austria, felt very surprised the first time it happened.
Ethereal_Keeper@reddit
My Freightliner cascadia will display and warn me if I’m too fast/slow, as nice as the feature would be I would like as much control over the drive as possible.
theFooMart@reddit
It exists. I know that Ford has it in some of their vehicles.
White_Lobster@reddit
Yeah, my Expedition has it. It's just ok. I don't like how it accelerates or brakes very aggressively when the speed limit changes. Also, it'll sometimes read a sign on an offramp and try to slow down to 45 on a 75mph freeway. It works, but you have to keep a close eye on it, which kind of means it doesn't work.
commeatus@reddit
2019 golf offered a "lane keeping assist" with their adaptive cruise control that also read speed limit signs and adjusted the cruise accordingly when activated.
ApolloWasMurdered@reddit
My Tesla does this, and I’ve driven rental Toyotas that do it as well…
Yuukiko_@reddit
I'd rather have a car station keep x amount of metres away from the car in front
Appropriate_Touch930@reddit
Need a max speed control
Ok-Entertainment5045@reddit
Why would I want to drive the speed limit. Dumb
thatdudewayoverthere@reddit
Good idea unless my car suddenly decides that it's 30 not 80kmh or that the 100kmh during rain means always
My adaptive cruise control gives a small alert and the option to change to the "seen" speed
gc3@reddit
And everyone driving behind you would hate you and you'd cause an accident
Phobos_Asaph@reddit
For driving the speed limit?
gc3@reddit
Cause everyone else is driving 85
Phobos_Asaph@reddit
There’s a passing lane for a reason. Drive safely.
gc3@reddit
You must be from the east coast
Phobos_Asaph@reddit
You must be quite the misanthrope
gc3@reddit
No, I just mean you must not drive on freeways in the west where the cops won't give a ticket unless you go 15 miles over the speed limt
Phobos_Asaph@reddit
I’m not saying drive below. I’m saying drive at. Also Florida
Arek_PL@reddit
yea, because carbrains think that going the speed limit causes accidents
MrBoomer1951@reddit
Your GPS knows your speed and it knows the posted maximum stored in the GPS map firmware.
ParentPostLacksWang@reddit
Just a chime when the detected speed limit changes (like most cars already do), and a dedicated button or sequence to change the cruise control set point to match the detected speed limit. That way false reads on speed limits remain a driver’s responsibility to detect and avoid.
There are plenty of roads that run parallel and cause false reads, car parks and drive-throughs that have speed limit signs but don’t have a matching normal speed sign at their exit, all sorts of reasons not to trust what the car thinks is the speed limit. I’ve been driving on the highway and had the car suddenly tell me the speed limit is 15 for 30 seconds. I definitely don’t want the car automatically obeying that by itself.
sopsaare@reddit
Don't most cars nowadays take the speed from the limit when you hit the CC? Tesla has done that for like a decade now.
Then again, the car, as all of them I have driven, sometimes misreads the signs and other times pulls weird shit out of its ass. Like 50Km/h in the middle of highway, l
FluidCommunity6016@reddit
My 2026 VW Tiguan has this feature. And it's always off, it's annoying, and it's dangerous.
stephanosblog@reddit
seems dangerous. for one thing map speed limits go out of date, plus there are construction zones set up, plus it's not always prudent to go the speed limit.
yogaballcactus@reddit
Newer cars use cameras to read the speed limit from signs, so the maps being out of date won’t matter. And, at least in my car, it’s amazing how accurate it is. I don’t think I’ve ever seen it mess up.
The only real issue is that it doesn’t know how fast to go when you pull from one road onto another until it sees a speed limit sign. You still need a human to look at how fast the other cars are going to make a decision to just drive the same speed as them.
stephanosblog@reddit
really ? "You still need a human to look at how fast the other cars are going to make a decision to just drive the same speed as them. " is that how you drive? in my state there is always a sign when the speed limit changes, and area speed limits are posted, in my development there are no speed limit signs except on the corners of the entry roads into the development. You simply have to know the speed limit for the area you are in once you are in it.
yogaballcactus@reddit
That’s how it works in every state. I’m talking about when you are on one road and make a turn onto another. There is not a speed limit sign at every intersection. And there is no such thing as just knowing what the speed limit is if it changes every couple of miles or if you’re not from the area. So yes, I drive at whatever speed everyone else is driving until I see a speed limit sign. If no one else is there or if they are going too fast for my comfort then I drive at a speed comfortable for the design of the road.
stephanosblog@reddit
there is literally no where in my county where i have to guess a speed limit.
yogaballcactus@reddit
I admire your commitment to your current level of understanding of this issue.
Sufficient_Result558@reddit
But certainly a smart car could determine what speed the other cars are traveling at, probably way before a human can.
rco8786@reddit
So just cruise control?
De1taTaco@reddit
I rented a Mini Cooper in Europe that did this. Honestly it would suck to drive every day, but it was great as an American in Europe trying to avoid a ticket after hearing how strict it can be.
autokiller677@reddit
Modern cars have this and it’s bad.
I drove a Audi from work recently. Left lane on the highway, 130km/h. The car sees the speed limit of 80 on the exit lane, adjusts the cruise control and starts breaking hard. Without warning. In traffic.
Nearly gave me a heart attack.
verygreenbananas@reddit
My Mercedes does this too! Turned that feature off immediately.
Rampage_Rick@reddit
I had a rental Ford Exploder in Edmonton with this "feature"
It would read the speed limit signs and adjust accordingly. If you set the cruise control to 10 above the speed limit it would keep you at 10 above the speed limit.
Problem is, Edmonton has a ton of "30 km/h while flashing" signs near pedestrian crossings. The system wasn't smart enough to figure out the "when flashing" part...
madTerminator@reddit
This is stupid. My Megane from 2020 detects signs but ask if I want to adjust speed and close that popup after few seconds. This speed limit mode is great on country roads with towns and villages along. I just set it on 50 and enable it in there.
ruinzifra@reddit
I don't want to go the speed limit. I want to go faster than that.
ThirdSunRising@reddit
I rented a Tesla and it had this. Automakers are putting it out there.
Count2Zero@reddit
My car has this today. It's pretty standard on VW models (VW, Audi, Porsche, Seat, SKODA). ACC (adaptive cruise control) keeps a constant distance from the car in front of you and adjusts the CC speed to the current road speed (cameras monitor the speed limit signs).
traumahawk88@reddit
Some day, we will see that. Tech isn't there yet.
I drive a brand new car with that HUD on it. Bought last fall with 37 miles on it. It is right most of the time, but not all. They don't like 'End 30mph' or similar signs and don't understand what that means. They treat the caution signs on corners as the actual speed limit. They don't pay attention to time of day for school zones.
A few more years and I think your idea will be standard though.
Your_As_Stupid_As_Me@reddit
Tesla auto drive?
KingBooRadley@reddit
My Model 3 does this just with the basic autopilot feature. It’s pretty great. Especially on little roads that go from highway to town and back again.
Sad-Celebration-7542@reddit
I wish Honda’s could read!
RogerRabbot@reddit
Just need to wait for AI to advance a bit more. Too often these things guess at the speed limit. My GPS likes to tell me unpaved gravel roads are 55mph.
Elemental_Garage@reddit
This has been a thing for over a decade in various forms.
unique_usemame@reddit
Plenty of cars have this. Sometimes they let you choose +5 miles an hour over (customizable) and sometimes by percentage (e.g. 5% over) and sometimes they let you pick between the two.
Some cars used to have that and then they removed the feature in an over the air update.
The biggest issue is when they get the speed limit wrong.
Some of them read speed limit sign.. and sometimes they confuse a 6 and 8 and make a mess as a result.
Some of them use gps data and look it up, but then you are on a freeway going over an overpass and suddenly it thinks the speed limit is 40.
Dayv1d@reddit
even my cheap peugeot does this. It can take the speed it reads from signs and put it as adaptive cruis control speed. I have to acknowledge it with one button press each time tho (the camera can make mistakes...).
ryzenguy111@reddit
many cars with more advanced driving assist features have this
SkyGuy5799@reddit
My Elantra would automatically change speed limits while also keeping itself in the lanes. I could be on my phone for miles
edgefundgareth@reddit
My ID3 had this
DragonFireCK@reddit
My car (2025 Kia EV6) actually has this as an option.
Once the cruise is set to the speed limit and the limit is at least 45, the car will adjust the set speed automatically to any speed at least 45. When it does so, it will beep.
It does behave poorly in some cases, especially construction zones. Sometimes I’ll be driving on the freeway and it’ll suddenly change from the actual limit to one 5 or even 10 off. Construction on one of the freeways has the freeway detour onto what is normally a ramp, where it randomly jumps between 45, 55, and 65 despite a constant limit of 55.
There is also the problem that it’ll only change the set speed automatically but after the sign, regardless of direction change.
cruffner01@reddit
Or just look at the street signs and adjust accordingly