Cruise control, but targeting a specific throttle position rather than a specific speed.

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Purple_Lurker-@reddit

Adaptive cruise control modulates the throttle.

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austinh1999@reddit

Regular cruise modulates throttle adaptive cruise maintains following distance

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LegallyIncorrect@reddit

What would this do that adaptive cruise control doesn’t already do? It will slow down and speed up to your max speed as traffic allows.

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This is so you are always burning X amount of fuel (or battery) per unit of time. If you’re going up hill, you go slow because you didn’t adapt to the incline. Downhill you’ll go faster because you are collecting on that potential energy

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LegallyIncorrect@reddit

Except that’s not how physics works. The engine has to work harder at equal throttle going up hill so it consumes more fuel when going uphill.

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Only_Information7895@reddit

At equal throttle the engine works just as hard as the throttle says how hard the engine works. So going uphill the car would lose speed till it stalls (manual) or downshifts (automatic).

Going downhill I would kinda just die. I already have to brake for sharper turns without even pressing the gas. Being at like 20% throttle will make me go so fast that I will just melt my brakes and crash in the 3rd turn as my brakes are literally glowing.

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LegallyIncorrect@reddit

Really? So the engine is working equally hard at 30% in second gear versus third gear?

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TedW@reddit

If we imagine the throttle like the spigot on a garden hose, it sets the fuel consumption rate, regardless of how effectively the engine converts that fuel into velocity. Higher throttle = more consumption, regardless of what gear or rpm the engine runs at.

Obviously being in the right gear and rpm range makes better use of that fuel, but it's being "spent" at the same rate regardless.

(Modern vehicles use computers to tune fuel injection based on dozens of factors like rpm, air temp, re-burning exhaust gasses, etc, but that kinda wrecks OP's whole question so let's assume it's a simple engine.)

A bicycle is a hard analogy because how do you measure a person's "throttle"?

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LegallyIncorrect@reddit

Except that merely opening the valve on a garden hose doesn’t guarantee the same amount of water flow at all times. Holding the throttle at one position does not guarantee the rpm of the engine will remain constant. It will go up and down.

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boofishy8@reddit

Work is energy. Energy is fixed for a given amount of fuel. Given the same amount of fuel, work will remain consistent.

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bocaj78@reddit

Is it more fuel than throttling up though? Because that is the comparison point

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LegallyIncorrect@reddit

I’m too lazy. That’s not an easy calculation because you’d reach the top with more momentum and inertia. I’m sure it’s more but it’s not linear.

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CO420Tech@reddit

It'd let you automatically hypermile and save on fuel... Your speed would be wildly variable in hilly terrain though.

Totally different than adaptive cruise control which holds a specific distance from other cars, not a specific throttle.

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The_R4ke@reddit

I think they're just thinking of adaptive cruise control.

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HalfEatenBanana@reddit

Lmao thank you I was thinking I swear I can already do this…

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BrainlessDipsticks@reddit

Hyundai/Kia have max speed mode.

Instead of setting a speed for the vehicle to hold you can set a maximum speed and continue controlling the throttle.

So you can slow down on hills if you need to but won't go above your set speed when it's over?

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Constant-Roll706@reddit

Just had a cocktail and couldn't figure out why you'd want a switch that tells a Kia to go as fast as possible...

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DetectiveNarrow@reddit

Lmao just smoked a jay and thought the same thing. I was like what fucking Kia needs a balls to the wall max speed operation?

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BrainlessDipsticks@reddit

Well ya know first grade reading comprehension helps.

You set a max speed. Not that difficult to understand.

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Pristine-Aspect-3086@reddit

they literally said they were a bit tipsy it wasn't a complaint about your phrasing

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BrainlessDipsticks@reddit

"ThEy LiTeRaLlY sAiD"

One cocktail? Holy shit featherweight.

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YouSmellSumthin@reddit

Why are you so fucking angsty, this is reddit my dude

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Constant-Roll706@reddit

Yes, it took 4 seconds for my brain to catch up on the first reading. But 'max speed mode' threw me for a moment

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Pleasant_Pen8744@reddit

But you have to keep pushing down the gas pedal the whole time?

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BrainlessDipsticks@reddit

Yes... Hence the ability to slow down...

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Quitcha_Bitchin@reddit

Motorcycles often have this. Semi locking throttle if you move it at all the lock disengages.

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KrispySal@reddit (OP)

Yes indeed. Not claiming to have invented this concept, just that it would be very convenient on cars, and it seems very unlikely to happen.

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ClacketyClackSend@reddit

It would be useless. Nobody does drive like this, so why do you think it would be so amazing? It's an idea that becomes more moronic the more you think about it.

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KrispySal@reddit (OP)

Ok

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copyandpasta@reddit

My sister had an ‘04 Suzuki 4 door that had a button labeled “hold” next to the shifter. If you press it while on the highway, the engine will attempt to hold around the range of RPM you’re currently at, as long as you keep some pedal applied.

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concerned_citizen128@reddit

That's how cruise control used to work. A vacuum pump would hold the pedal where you put it. Problem is hills mess it up. Also, transmissions shift and will change your speed, and everyone's speed will change at different times.

Current tech is way better with radar cruise.

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TheTrampIt@reddit

In the past, long time ago, Fiats came with a hand throttle, so the driver can adjust idling speed based on altitude or weather.

If turned fully on the car would rev at 3000 rpm.

I did use it, occasionally and without traffic as a poor man’s cruise control. The main issue were slopes: while keeping a decent 100 km/h on flats, uphill it would slow down to stalling while downhill it would go at dangerous speeds.

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dr_reverend@reddit

That is literally what the first versions of cruise control were. They just locked the throttle into a specific position. Can you guess why they don’t exist anymore?

I really don’t understand your reasoning for it though.

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Ben-Goldberg@reddit

Boats often have this

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germanstudent123@reddit

I mean how often do you find yourself going uphill on a boat?

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PeachPuffPrincessa@reddit

It would feel amazing for like 10 mins until you realize you’re either crawling uphill or accidentally reenacting the fast and furious downhill.

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SolidOutcome@reddit

It's what semi trucks do, you'd be able to flow with them a lot better

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germanstudent123@reddit

I mean you could just activate adaptive cruise to a very high target speed and it will stay behind the truck all the same

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sgtnoodle@reddit

Isn't that just putting your foot on the pedal and zoning out?

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anakhizer@reddit

I actually don't understand why no car seems to have multiple saveable speed for CC - it would make highway trips so much more comfy

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Veezer@reddit

Yeah, when cruise control became common on cars in the early 70's, that's exactly how it worked: clamping the throttle.

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Crab-_-Objective@reddit

Older cruise control was exactly this. It locked the throttle/engine at the current RPM and you’d sped up/slow down going down/up hills.

It got phased out because 99% of drivers want consistent speed.

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porcelainvacation@reddit

My 1950 Chevy pickup truck has this, it’s called a hand throttle. It’s mainly useful for starting the engine in cold weather (in conjunction with the choke) and puttering around a bouncy field.

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Darkknight145@reddit

Not practical in a real world situation. You'd slow down going up hill and speed up going down hill most likely breaking the posted speed limit, I'd hate to be driving behind you with your speed constantly varying.

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SolidOutcome@reddit

It what semi trucks do already

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gloriouspear@reddit

Haven't seen it in cars yet, but this would be the most fuel efficient way of driving especially in hilly terrain.

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181513@reddit

Adaptive Cruise Control and Ride Modes with Electronic Throttles are a feature on many bikes.

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haruuuuuu1234@reddit

Lots of cars do this. Especially zee German ones because they like accuracy. Older German manual transmission cars usually had vacuum operated cruise control that would attempt to keep the RPM constant. It's MUCH more accurate than speed based options. I've driven 80's German cars over mountain passes, never touched anything other than the steering wheel and the speed only changed by +/- 0.2 MPH going up and down steep ass hills.

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Sorry-Climate-7982@reddit

Sigh. Ever hear of a hand throttle? Many early vehicles didn't have a gas pedal at all, but a hand throttle was still available in 1970 [Datsun 2000]

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LegallyIncorrect@reddit

Still available in military humvees today. It’s meant to idle it up (it has a real pedal too) but people have used them as cruise control forever. The issue is they don’t disengage when you hit the break.

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Any_Ring_3818@reddit

Mine had a label that very clearly said it wasnt for Cruise Control.

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LegallyIncorrect@reddit

Of course it did, but you used it anyway right?

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Sorry-Climate-7982@reddit

Yeah, that is one of the reasons you don't see them any more.
But military vehicles aren't really bound by NHTSA

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LegallyIncorrect@reddit

Not “aren’t really.” They aren’t bound at all. There is also a switch to turn off all lights, including break lights. And no airbags.

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Any_Ring_3818@reddit

I know what you mean but it did more than turn off all lights. The black out modes were very cool.

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KrispySal@reddit (OP)

It would seem that this is unavailable on cars today, which is what I'm suggesting. Sorry if that wasn't clear?

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Sorry-Climate-7982@reddit

It can be a safety problem and even if not, requires a driver with a pulse to remember to turn the thing off or down when changing gears. The older ones that you could lock in place [which would be required for your purpose] are prohibited by standard 124. You can install one if disabled with restrictions on who can do it, driver license notation, doctor note etc.

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screwedupinaz@reddit

That would mean that all vehicles would have to have the exact same aerodynamics and powertrain. Example: If a sportscar with 400 HP is holding 65 MPH begins to go up a hill, it will go faster than box truck with 100 HP that started going up that same hill when it started the hill at 65 MPH, assuming the throttle position didn't change.

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