Why are vehicles made to go very fast if the speed limit is so low compared to what speed vehicles can do..?

Question

I mean if vehicles were powered to do under 100kph or whatever speed the limit is..
Would it not save a lot of lives and less crashes if the were build to only go as what the speed limit allows..

Answer 1

Not everywhere has speed limits.



Speed limits can be changed arbitrarily by politicians much quicker than car manufacturers can develop new cars, so no manufacturer will take the risk of being left looking silly be a legislative change.



With internal combustion engines and multi-speed transmissions (i.e. normal cars) the high top speed is actually a by-product of producing a car than can both accelerate quickly up to the speed limit (using high power in low gears) and cruise quietly and efficiently at that limit (using low power in high gears). With electric cars multispeed transmissions are generally not needed, so the same issue doesn't occur, which is why some of the fastest accelerating cars are electric cars that, while capable of quite high speeds don't have the same high top speeds of similarly powerful combustion-engined cars.

Answer 2

Some U.S. 18 wheeler tractor/trailers do just that. They are geared properly for good fuel economy and with good acceleration, but the computer is set with a maximum engine speed that limits the top speed. The computers can actually be set to limit the top speed in each gear if desired.



The problem is that if you set a car for one max speed and then take it somewhere with a higher max speed allowed, the car can't do the new speed. Another problem is that some people insist on being able to drive faster than speed limits and there will always be someone who will figure out how to "modify" the computer to bypass the set max speed. (After market companies in the U.S. sell specialty "chips" that plug into stock computers and change their settings, while a computer's parameters can be changed by anyone with the proper software and engine and thus road speeds can be changed.)



You can also do that mechanically by changing the size of the tires (larger diameter means the car goes further for each revolution of the engine, which means it will go faster) and gearing can be changed that allows for faster road speeds versus engine speeds. IE: if a vehicle with 3.90:1 final gearing can max at 100 kph, that same vehicle with everything the same except using 3.55:1 final gearing will be able to reach 110 kph. It won't accelerate as quickly, but will be able to have a higher top speed.



Years ago, U.S. built 18 wheelers were designed so that they had a max speed of 55 mph, or 88 kph. (national speed limit at the time) That was before the days of computer controlled engines so it was done by either putting a mechanical stop on the throttle linkage so that it couldn't go as far as it should, or by putting gearing in the differentials that set the engine's max speed to give a road speed of 55 mph. The mechanical stop could be removed, so that didn't work very well, and the gearing for a maximum speed of 55 mph meant the engine was running at its maximum speed, which results in its worst fuel efficiency and highest stress points at all times.



My 1977 GMC 18 wheeler maxed at 55 mph in the top gear at 2100 RPM versus my 2005 Western Star 18 wheeler that maxed at 119 mph in top gear at 2100 RPM. The 1977 gave 4 miles per gallon of fuel @ 55 mph while the 2005 gave almost 9 miles per gallon of fuel @ 55 mph and could run at the up to 80 mph (129 kph) speed limits in parts of the U.S while still giving 7+ mpg.



It is my job as a driver to NOT run my engine at its maximum. The best speed limiter is that nut behind the steering wheel acting like a responsible adult.

Answer 3

Just because the speedometer dial goes up to 120 or 130 mph doesn't mean the car can actually go that fast. If you tried to limit all cars to under 100kph, (62 mph) there would be a LOT of pissed off people because on SOME highways, the LEGAL speed limit is a lot higher than that.

Answer 4

Most accidents happen at speed limit or below. High speed accidents account for only a small fraction of all car accidents. However, they're the ones you hear about most often because they are more serious.

Answer 5

Acceleration. If you want to be limited to 100 kph, go get one of the original VW Beetles and see how long it takes to get to speed.

Answer 6

maybe because the cars have engines needed for their weight. so they don't feel underpowered and can carry luggage and people.

Answer 7

That's a great idea. Next up, for public safety of course, no one is allowed to carry or own weapons. You see where I'm going with this?



There would be a lot less crashes if people actually paid attention to driving, if they drove the speed for the road conditions, didn't follow to close and so on.

Answer 8

Cars are made for performance in other areas. People want good acceleration, and low fuel consumption, and this is done by making the engine more powerful and decreasing the drag. In turn, this means that the cars have a faster top speed. Cars that are made to be fast, like Lamborghinis and Ferraris are not made for driving to the shop, they're made for driving on private roads, for racing or leisure.

Answer 9

I am not a mechanic or engineer, but as I understand it, it is better for an engine not to be running at full capacity, so less wear and tear on the engine.

Answer 10

no

Answer 11

Because speed, gender, and age are directly inverse proportions.

In other words a 16 YO male would love to do 100 MPH whenever.

But a 25 YO guy is far more conscientious, usually.

Since we girls lack powerful, risk taking, testosterone, we could care less.



Auto sales are also power related.

Guys like power at all ages even if they don't use it much.

Men approaching 65 YO often purchase the ultimate "crisis car" the Corvette,

and typically drive it back and forth to work at mundane speed.



But, who doesn't love cars!

Answer 12

To sell to idiots (mostly male) that want a "fast car".

Answer 13

well its just like if you have a free supply of alcohol you shouldn't drink whole of it because you kind of leave the world, the same goes for the speed limit. Just because your vehicle can go fast then you have to drive fast too to kind of leave the world forever

Answer 14

Plenty of reasons why. For one, there's no speed limits at race tracks, and some people track their cars on the weekends. Also, passing power. If your vehicle can only do the speed limit, and you're stuck behind a car doing 10under the speed limit, it's likely you won't be able to pass them safely even in a passing zone. Another reason is changing speed limits, and different speed limits in different places. We use miles here, but 100kph equates to 62mph, there are multiple roads I drive on every day with speed limits of 65 or even 70mph. There's roads in other states with 75mph, or even 80mph speed limits. There's the infamous autobahn over in europe without speed limits on most of it. If your vehicle could only do 100kph(62mph) then you would likely get run off the road in those areas, and it would be even more unsafe to be driving so slowly in such a high speed area. You also likely wouldn't have any extra power for getting up hills, or for carrying passengers and cargo, etc. There's also the issue of how to restrict a vehicle. If you design it with a electronic restriction(meaning it's capable of great speeds but the ECU won't let the car go those speeds) then inevitably someone will figure out how to disable that restriction, and then it's a wasted effort. If the car is designed that mechanically it can't go faster, then you run into an issue with wear and tear on the engine and the cars longevity, because normal driving would then be a lot tougher on the engine as it'd be right at the edge of its limits all the time. Having a vehicle capable of higher speeds means that average driving keeps the rpms on the engine lower, meaning less stress on the engine. And if there was a legal mandate made that every new car had to be limited to such a low speed, plenty of people would simply refuse to buy a new car, and instead rebuild older cars without the restriction. So that would in essence kill the car companies. Also, in emergency situations having a car restricted to a low speed could potentially cause more deaths(people needing to get to a hospital quickly could die on the way there because the vehicle couldn't go fast enough). Could keep going with plenty of other reasons why it's really a bad idea, but if you don't understand why now then more reasoning isn't going to help. And most crashes are due to people simply not paying attention, regardless of speed, so I really doubt that restricting the speeds cars can do would have any effect on how many crashes there are.

Answer 15

Several reasons.



If you have a car that only has enough power to do the speed limit, it takes all day to get to that speed, and if you get to a hill, or are carrying a load, or there is a headwind... Now you and your friends are crawling up the mountain road at 40 kph being passed by farm tractors.



A car with only that much power will need to be driven at full throttle to just maintain cruising speed. How long do you think it will last?



And a safety concern. If you are following, say a heavy loaded truck, and it's travelling at 50-70kmh because of the hills and corners. (sensible truck driver). But you want to to drive at the speed limit of 100k, because it's safe in your car. Now a nice safe stretch of road comes up, where you can overtake the truck, now doing it's max speed of 90ks. Are you going to be safe crawling past the truck at 99kmh, once you actually build up to that speed? Remember another truck can come around the corner any moment, so you want to get up to speed, past the truck and back into your lane as quick as you can. That takes more power, and in that situation a speed limiter would make things MORE dangerous, but keeping an otherwise safe driver stuck out on the wrong side of the road for twice as long as they should be.



And lastly, no one would actually buy a car like that....

Answer 16

If you follow this to its logical (!) conclusion, vehicles should not be allowed to run at all, therefore saving the maximum number of lives.



Now get out of the left lane.

Answer 17

I would be reluctant to buy it. I have on occasion topped out just about every vehicle I've owned.

Answer 18

Drove a rental truck across country. The engine had a governor that would let the truck do 55 MPH and no faster. ONCE. I never went back with that company again.



Would you buy a car that was governed to go no faster than the max speed limit? Unless it was all I could afford, my answer to that question would be a resounding "HELL NO!".

Answer 19

Put it this way, if you were going to drive at 100km and you could just make it, the car would be at its limit, things would go wrong and overtime the vehicle would just blow out. A vehicle going at only half of what it can go will mean less strain and its just more convenient.