I think I understand that driving faster increases drag because there’s more air pushing against your vehicle, but why is the drag for that distance greater at higher speeds? If a car is driving slower but across the same distance, wouldn’t the total impulse created by the drag be the same as going faster because it’s delivered over a greater time, even though it’s a smaller force at any given moment?
In: 3
No matter what the gearing is, the increase in RPM (thus the amount of fuel sprayed per turn) will always be greater than the increase in circumference driven by the wheels.
So say you increase the engine RPM from 2k to 3k RPM, your consumption increases by 50% but your car will go from 60 to 75 MPH (an increase of roughly 25%). You are burning more fuel than you are getting speed for it.
You now see how manufacturers can only focus on gearing the transmission so 60mph is linked to when the engine is at its lowest drivable gear ratio (you still have to pass cars and go up hills so it can’t be too low) race cars can have an other “speeding” gear that would be useful at higher speeds and saving more fuel at 60 mph but it would also lack power as the engine would be at a very low RPM to accelerate confortably.
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