You need close to three times (2.78) the energy for accelerating to 50 instead of 30.
If you have to brake, that energy gets converted to heat.
Rinse and repeat. Especially in urban areas where there’s alot of acceleration/deceleration - or just acceleration with different algebraic signs - more speed means more fuel per distance.
There are several graphs floating around showing the fuel consumption at 30 compared to 50 with different gears. It depends on your car and the gear used if 30 uses more fuel than 50. If your car uses more fuel for slower speeds and for such a common speed as 30, the manufacturer is an idiot. There are so many 30 zones in Europe that it really is not an argument against them that a car manufacturer can’t build proper cars.
And since we are also switching to electric cars, that problem will go away in the next decade or two.
If your car uses more fuel for slower speeds and for such a common speed as 30, the manufacturer is an idiot.
Or the manufacturer just optimized the engine and the gearbox to be more efficent at a certain speed.
In the end the consumption is tied to the rpm of the engine, if you need to stay on high rpm to go to 30 km/h on a lower gear because the gear ratios are optimized thinking to a certain set of speeds (50, 70, 90 and 130 km/h which are the most common in EU), you will end with a higher consumption.
That’s exactly what I wanted to say: 30 is one of the most common speeds in the EU. They are not new and have been around since the 70s/80s. Cities are pushing for 30 as a default speed. You have thousands and thousands of kilometres of residential streets with T30. If you do not optimize for that as a manufacturer, you shouldn’t build cars.
That’s exactly what I wanted to say: 30 is one of the most common speeds in the EU. They are not new and have been around since the 70s/80s.
As far as I know, the city speed limit is 50 km/h for a very long time. In the 199x, when I got my driver license it was it, the push for the 30 km/h limit is a relatively new thing, maybe last 5 years. Not to say that before there where not some 30 km/h zones in cities, but the default in every urban center (small or big) is/was 50.
Cities are pushing for 30 as a default speed.
Now yes, but is a relatively recent thing, and only for big cities.
You have thousands and thousands of kilometres of residential streets with T30. If you do not optimize for that as a manufacturer, you shouldn’t build cars.
Italy currently has an estimated total 2700 km of 30 km/h residential streets. My city alone (Milan) has about 58.0000 km of streets (only residential streets, the total is way higher).
Maybe manufacturer are not that dumb if they do not optimize the engine for the equivalent of the (less then) 5% of the streets of just one city in a state.
And I suppose that other states are in a somewhat similar situation.
Lower speed limits also yielded environmental benefits, with emissions decreasing on average by 18%, noise pollution levels by 2.5 dB, and fuel consumption by 7%, indicating enhanced fuel efficiency and reduced environmental impact.
In this study they did not look into the reduction of particulate matter from tire and brake abrasion, which is a major source of pollution caused by cars, so the environmental benefit is even greater than they found.
I agree, but we are discussing why manufacturers are not idiot to not optimize engines for the speed limit of a very (for now, I agree) percentual of the streets.
Data on this is based on highway driving. Not city driving. Acceleration to 50 and then breaking again will be much less efficient than just driving a in 30
Technically it does. Engines are usually less optimized for driving 30 compared to 50, which causes them to use more fuel for the same distance.
But a slightly higher fuel consumption is easily offset by reduced noise and increased safety (for everyone).
You need close to three times (2.78) the energy for accelerating to 50 instead of 30.
If you have to brake, that energy gets converted to heat.
Rinse and repeat.
Especially in urban areas where there’s alot of acceleration/deceleration - or just acceleration with different algebraic signs - more speed means more fuel per distance.
There are several graphs floating around showing the fuel consumption at 30 compared to 50 with different gears. It depends on your car and the gear used if 30 uses more fuel than 50. If your car uses more fuel for slower speeds and for such a common speed as 30, the manufacturer is an idiot. There are so many 30 zones in Europe that it really is not an argument against them that a car manufacturer can’t build proper cars.
And since we are also switching to electric cars, that problem will go away in the next decade or two.
Or the manufacturer just optimized the engine and the gearbox to be more efficent at a certain speed.
In the end the consumption is tied to the rpm of the engine, if you need to stay on high rpm to go to 30 km/h on a lower gear because the gear ratios are optimized thinking to a certain set of speeds (50, 70, 90 and 130 km/h which are the most common in EU), you will end with a higher consumption.
That’s exactly what I wanted to say: 30 is one of the most common speeds in the EU. They are not new and have been around since the 70s/80s. Cities are pushing for 30 as a default speed. You have thousands and thousands of kilometres of residential streets with T30. If you do not optimize for that as a manufacturer, you shouldn’t build cars.
As far as I know, the city speed limit is 50 km/h for a very long time. In the 199x, when I got my driver license it was it, the push for the 30 km/h limit is a relatively new thing, maybe last 5 years. Not to say that before there where not some 30 km/h zones in cities, but the default in every urban center (small or big) is/was 50.
Now yes, but is a relatively recent thing, and only for big cities.
Italy currently has an estimated total 2700 km of 30 km/h residential streets. My city alone (Milan) has about 58.0000 km of streets (only residential streets, the total is way higher).
Maybe manufacturer are not that dumb if they do not optimize the engine for the equivalent of the (less then) 5% of the streets of just one city in a state.
And I suppose that other states are in a somewhat similar situation.
Review of City-Wide 30 km/h Speed Limit Benefits in Europe
In this study they did not look into the reduction of particulate matter from tire and brake abrasion, which is a major source of pollution caused by cars, so the environmental benefit is even greater than they found.
I agree, but we are discussing why manufacturers are not idiot to not optimize engines for the speed limit of a very (for now, I agree) percentual of the streets.
My car is either lugging along in 2nd gear or doing like 3500 rpm in first at 30 kph, so mine wouldn’t be any quieter.
At that speed, most of the noise comes from the tyres. Slower = quieter.
Not with my exhaust
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That’s just not correct
Which part? Can you be more specific as to what you mean?
Data on this is based on highway driving. Not city driving. Acceleration to 50 and then breaking again will be much less efficient than just driving a in 30
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