Does this advice apply to all cars?
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braking slowly extends the life of your break pads, and accelerating slowly reduces the amount of gas you burn at a time because pressing the pedal doesn’t increase speed it increases acceleration
As for breaking gradually I don’t think that in itself saves gas. But if you see a red light up ahead instead of keeping your foot on the gas until you are close to the light then break suddenly will consume more gas than if you take your foot off the gas ahead of time and gradually slow down before coming to a stop. So less time with foot on gas = less gas usage.
Difficult to ELI5 because it’s involving physics/math, but I’ll give an analogy.
Let’s say you’ve got a shopping cart loaded up with items. It’s hard to push, but with a little lean it will start moving and by the end of the aisle you’ll be pushing at a good walking speed, and it was never exhausting. Now if you wanted to get that cart up to walking speed really quickly, then you’d really need to shove into it hard, and this would be tiring overall even though it’s over quickly.
So if you want your car to move fast, you need to burn a lot of gas! This actually burns more gas then letting it gently speed up over more time.
It’s all about avoiding unnecessary acceleration. Taking your foot off the gas without braking means you don’t waste gas on unnecessary acceleration. Accelerating into a stop just wastes gas.
Similarly, accelerating gently means you don’t waste gas on unnecessary acceleration, or indeed waste gas without any appreciable increase in acceleration. Accelerating gently means inertia works with you, and it ensures that your engine works efficiently.
You engine uses NO fuel when coasting with your foot off the pedal. The greatest amount of fuel is used during acceleration from a stop or starting the engine cold. By coasting and avoiding stopping at lights you can significantly improve mileage.
optimal fuel air mixture is lambda=1 (around 14:1 air-fuel mixture)
everytime you accelerate you will enrich the mix with more fuel … lambda <1, meaning the efficiancy gets reduced. when you reduce throttle the mix goes to a lean fuel mix, lambda>1 or nowadays fuel gets completely shut.
So best strategy is to keep acceleration time short and switch to higher gears early.
conservation. performance requires extra energy when you can just go average speed to reach the same point maybe a little later.
Nobody has mentioned the other benefit of coasting to slow down: less wear and tear on the brakes.
Brakes won’t make any significant difference on mileage. Except that, if you come to a stop versus a slow roll the engine has to work that much harder to accelerate. Which is why highway mileage is better than what you get in town.
Engines require a combination of air, fuel, and spark to make explosions. The faster you accelerate, the more air and fuel is needed by the engine in order to make a bigger explosion which is the energy used to crank the wheels. Hence, worse mileage.
When a car is stop, it has no moving energy. When a car is moving, it has energy. The faster a car is moving, the more energy the car is having. We use more gas to move a car faster.
A faster car gives away more energy to the ground and the air.
When a car is moving, it slows down without stepping on gas and break. The energy goes to heat and moving the air around the car and the ground underneath the car.
If we step on break harder, more moving energy of the car is turned to heat on the break and on the ground. This mean the energy used to move the car faster is wasted on heat than on moving the car.
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