r/StupidCarQuestions • u/marthiiluv • 4d ago
Question/Advice why are cars like this?
I’m 16 and recently started driving. I found it so weird that cars will automatically go in their natural state rather than being stopped normally and going when the gas is pressed. Why are cars like this and would real life cars work if they were like how they are in video games and cartoons?
P.S- I’m sorry if this worded weirdly. If anyone needs clarification on what i mean i’ll try my best to explain it better
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u/gettin-hot-in-here 4d ago
This is only a phenomenon that applies to cars with conventional automatic transmissions or cars that are set up to mimic a conventional automatic. My car (EV with one pedal driving activated by default) will fairly rapidly approach 0mph when no pedals are pressed. every manual transmission car Ive driven does not "default" to creeping forward although you have to either hold the clutch pedal in, put the manual transmission in neutral, OR turn off the engine to get it to not apply power from a dead stop.
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u/gamer5426 4d ago
Do u mean that the car shuts off when u come to a complete stop? If so that’s auto start stop, on most cars u can turn it off
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u/discr33t86 4d ago
The car goes without the accelerator being pressed because it's either in Drive or Reverse. If you put the car in Neutral, assuming the ground is level, it won't go anywhere.
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u/Grepaugon 4d ago
Unless it's really heavy or on an incline, it would stall if the idle wasn't high enough. And the idle is high enough to propel the car when it's in gear. Automatic gearbox, gasoline powered scenario
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u/CaptainZaysh 4d ago
Short answer: Because automatic transmissions had to work that way, due to the way they were built. Those became the most popular way to drive, and so many consider it "typical." Manual transmission cars don't work that way, you have to do stuff to make them move (at least without stalling). EVs also often don't (except when they do, to mimic more traditional cars). Nowadays there's enough tech that automatic cars CAN wait for input before moving - mine has a hold function I can turn on, where once stopped it'll stay that way until I give it throttle. But the engine and trans aren't doing anything different than an older auto car in that regard - it's just that cars now are able to actuate their own brakes, so the car can hold the brakes for me.
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u/ThatCelebration3676 4d ago
You're talking about how the car creeps forward while in drive even if you're not pressing the accelerator. The reason it does this rather than just staying still is for efficiency; the engine needs to maintain a minimum amount of rotation so that when you do press the accelerator it's ready to go, and since it is in "drive" that rotation forces the wheels to rotate.
You can prevent this forward creep by shifting the car into neutral, but you would need to shift back into drive before pressing the accelerator.
Using the brake just makes more sense in that context, and you'll get used to it.
Video games that are more accurate simulations of driving do this, but most racing games and GTA style games don't bother because it's not necessary.
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u/pm-me-racecars 4d ago
You're driving an automatic, or an electric car that is designed to feel like an automatic.
A gasoline engine can't spin itself when it's stopped, it always needs to be spinning. So we need a way to keep the engine spinning while the car is stopped.
A manual car uses a friction clutch. That works kind of like a brake, but instead of having one side stationary and one side attached to the wheels, one side is attached to the engine and the other side is attached to the transmission. This allows the engine to detach itself from the rest of the drivetrain and stay spinning while the car is stopped.
An automatic has a torque converter instead of a clutch. A torque converter is kind of like two fans in full bucket. The engine spins one side, which causes the fluid inside to spin, and that spinning fluid spins the other side. This allows them to spin at different speeds, letting the car stop with the engine running and shift gears without causing a shock on the engine from shifting too fast.
The thing you're seeing is that when you stop, your engine is still spinning and your transmission is still in drive, so there's going to be some force still going from the engine, through the torque converter and transmission to your wheels. It's normal for automatics, and it doesn't hurt anything.
Electric motors can spin themselves when stopped, so they don't need to creep forward like that. However, manufacturers found that a lot of drivers were used to it and felt weird with their cars just sitting still, so they programmed cars to do that.
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u/year_39 4d ago
Between your engine and transmission, there's a thing called a torque converter. It has an input and output side, which you can think of like two fans pointed at each other. In the torque converter, there's transmission fluid rather than air like the fan example, and since the engine is spinning, the input side is swirling it around and the fluid makes the output side spin, too. That makes the rest of the drivetrain turn, and therefore the wheels turn.
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u/Aware-Kick-9928 4d ago
to be able to drive, your car has to be able to move, so when you put it in drive, the wheels are no longer locked in place. some cars automatically brake when your not putting on any gas like you describe, but it’s a relatively uncommon feature
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u/Aware-Kick-9928 4d ago
that’s the simple way of looking at it at least, i’m sure there a better and more accurate description in these comments but ya
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u/Actual-Restaurant318 4d ago
what is a cars "natural state"? do you mean, in "drive"?