When I first started driving I drove slow bc I thought it would save gas, then I started driving faster when a friend told me you use the same amount of gas whether you drive slow or fast (as long as it’s the same distance), you just would be driving fast for a shorter amt of time and driving slow for a longer amt of time, but at the end you burner thru the same amount of gas. Is this true?
In: 5
Depends on the speed and the car and the tires
The amount of fuel you burn depends on how much power you need, and how much fuel your engine burns just to keep running. All engines consume some fuel just to overcome its own resistances and keep spinning, if you drive too slow then this is the main cause of fuel consumption and you get terrible fuel economy
How much power you need depends on the rolling resistance of the car and the air resistance. Rolling resistance doesn’t change with speed so it takes the same force at all speeds and therefore twice as much power to go twice as fast. Air resistance changes with the square of speed so the power to overcome it goes up by 4x if you double the speed.
If you add the fuel per minute require to keep the engine spinning + fuel to overcome rolling resistance + fuel to overcome air resistance and plot that out across speed, you’ll have a point where you cover the most distance with the least fuel but what speed that is at depends on the car
A car on low rolling resistance tires is going to fare better at middle speeds (20-40mph) than a car with big wide grippy tires that have great traction but high rolling resistance, but that car with the big wide grippy tires might be a lot more aerodynamic have have less wind resistance at highway speeds
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