What is the most fuel-efficient speed to drive at?

The Energy Saving Trust says that the most efficient speed you can travel in a car in terms of achieving the best fuel economy is 55-65mph. Any faster, though, and the fuel efficiency decreases rapidly. For example, driving at 85mph uses 40% more fuel than at 70mph (oh, and it's illegal too).
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Why is 55 mph the most efficient speed?

The most efficient speed for electric cars is closer to 15-20 mph versus 55 mph for ordinary cars. This is because the losses at low speeds for ordinary cars has to do with the construction and inefficiency of the gas ICE. Directly to the question at hand - they also give the sources of losses over the range of speeds.
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Is it more fuel efficient to drive fast or slow?

Slow Down and Drive Conservatively

Speeding increases fuel consumption and decreases fuel economy as a result of tire rolling resistance and air resistance. While vehicles reach optimal fuel economy at different speeds, gas mileage usually decreases rapidly at speeds above 50 miles per hour (mph).
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Why is 56 mph the most economical speed?

Over the years the speed of 56mph has often been talked about as being the optimum speed. This was due to the old fuel consumption test being run at three speeds: urban, 56mph and 75mph – and 56mph was always, unsurprisingly, the most efficient of these.
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Does driving at 60 save fuel?

“We found that limiting your maximum speed to 60 MPH reduces your fuel consumption by 10%,” said Simon East, CEO of DriveGain, “but that this only adds 2 minutes to the average journey time”. “We find drivers tend to over-estimate how much quicker they will arrive when driving faster”, he added.
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The Most Efficient Driving Speed - An MPG Experiment



Does driving at 50mph save fuel?

The Energy Saving Trust says that the most efficient speed you can travel in a car in terms of achieving the best fuel economy is 55-65mph. Any faster, though, and the fuel efficiency decreases rapidly. For example, driving at 85mph uses 40% more fuel than at 70mph (oh, and it's illegal too).
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Is 70mph fuel-efficient?

Fact #982: June 19, 2017 Slow Down to Save Fuel: Fuel Economy Decreases About 14% When Traveling at 70 mph Versus 60 mph. Between 40 and 50 miles per hour (mph) is the optimum cruising speed for high fuel economy in cars and light trucks according to an Oak Ridge National Laboratory study of 74 different vehicles.
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What wastes the most gas in a car?

Driving too fast.

Most American cars operate at peak efficiency—generating the most forward momentum with the least amount of fuel—between 50 and 60 miles per hour.
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Does accelerating quickly save fuel?

The best acceleration rate varies with the vehicle, gear ratios and weight. But in our testing we found that taking 15 seconds to accelerate to 50 mph used less fuel than taking 30 seconds to reach the same speed, because the car entered its top, fuel-saving gear sooner.
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Does gas burn slower on a full tank?

Reducing the weight of your car by 2.5% (by only filling your tank half full) would not have a noticeable effect on your fuel consumption. When all is said and done, there isn't a huge difference in fuel consumption, but there are some definite pros to filling your tank.
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Does cruise control save gas?

Generally speaking, yes. Cruise control can help you become more fuel-efficient and can help you save an average of 7-14% on gas thanks to its ability to maintain a continuous speed. In comparison, the constant change in acceleration and deceleration of the driver placing their foot over the pedals can eat more gas.
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Is gas mileage better with a full tank?

per gallon), so even in most large vehicles the total weight of a full tank is under 250 lbs. Your car may actually be less efficient when the tank is near-empty, as more air in the tank can increase fuel evaporation.
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How do you drive fuel efficiently?

Fuel-efficient driving techniques
  1. Accelerate gently. The harder you accelerate the more fuel you use. ...
  2. Maintain a steady speed. When your speed dips and bursts, you use more fuel, and spend more money, than you need to. ...
  3. Anticipate traffic. ...
  4. Avoid high speeds. ...
  5. Coast to decelerate. ...
  6. More ways to use less fuel. ...
  7. Challenge yourself.
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What wastes fuel in a car?

Braking and accelerating sharply can waste fuel, so consider (as should be done anyway) a sensible, cautious approach to driving which avoids the need for sharp braking. A more consistent approach to your speed will also help to lessen fuel consumption.
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Does it save gas to not use AC?

Your engine warms up to an efficient temperature faster; summer grades of gasoline can have slightly more energy; and warm air causes less aerodynamic drag than cold air. However, keeping passengers comfortable in hot weather by rolling down the windows or using the air conditioning (AC) can reduce fuel economy.
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Does AC burn car gas?

Does your car's air conditioning (a/c) use gas? Yes — like many of your car's features, the air conditioning system does consume fuel. Car dair conditioning works by drawing energy from the alternator, which is powered by the engine.
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Does turning off your car save gas?

Unless you drive a vintage, carburetor-equipped vehicle, you'll save fuel and reduce carbon dioxide emissions by turning it off. Some drivers think that idling uses less fuel than restarting, but our research has found that drivers save fuel and reduce emissions by shutting down for stops as brief as 10 seconds.
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Does accelerating quickly hurt engine?

Hard, or rapid, accelerations add stress to the engine and transmission, burning fuel more quickly. When drivers “gun it,” the vehicle sees that as a request for a power boost, burning more fuel than the driver would actually need to reach the same speed more gradually.
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Is 85 mph too fast?

Safe Driving

Instead of slowing down in rain, fog or darkness, most of the drivers will maintain the pace just like they do on other highways. An 85 mile per hour speed limit is a recipe for disaster. Regardless of how well engineers construct the road, the highway is unsafe for the people who will use it.
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At what speed does mpg drop?

Speed Kills MPG

Your car's gas mileage decreases once it gets past its optimal speed. For most cars, this is around 55-60 mph. This means that every time you go over this speed, you're essentially wasting gas and money - and creating unnecessary greenhouse gases.
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How much more fuel is 80 than 70?

That said, obviously, you should drive at speeds appropriate to the road you are on. Similarly, if you break the speed limit and travel at 80mph, your car will use up to 25% more fuel than at 70mph, according to What Car?
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How much more fuel does 70 or 50 use?

Explanation: Your vehicle will use less fuel if you avoid heavy acceleration. The higher the engine revs, the more fuel you'll use. Using the same gear, and covering the same distance, a vehicle travelling at 70 mph will use about 15% more fuel than it would at 50 mph.
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What uses the most fuel in a car?

Maybach 57 is a luxury rhino-like vehicle fitted with a 6-litre V12 engine that consumes 1 litre per 5.7 km on a highway. Bentley Meteor is officially recognized as “the most fuel-hungry” vehicle in the world. To go 100 km, it requires 117 litres of fuel.
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What rpm should a car drive at?

The idle speed should feel consistent without skipping or slipping. In most of today's cars, an idle speed of 600 to 1000 RPMs is average. If your car is idling rough, though, it won't feel smooth. The RPMs will jump up and down, for example, or they'll fall below 600 RPM (or whatever is typical for your vehicle).
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At what engine speed revs should you change gear to get the best fuel economy without straining the engine?

Change up earlier – don't labour the engine but try changing up at an engine speed of around 2,000 rpm (diesel) or 2,500 (petrol). Since 2014 new car models have been fitted with a gear shift indicator to encourage use of the most efficient gear.
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