Off Topic — HabitableZone

Off Topic » in reply to Wait...

Much better numbers
SDF — (archived)

Kia Rio gets 35 mpg at 60 mph.

So it consumes 1.7143 gallons of fuel in 1 hour.

Gasoline has 31.6 MJ energy per liter, and there are 3.79 liters per gallon.

Total fuel input is 57 kW (76.45 hp).

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From Wikipedia: "Most gasoline fueled internal combustion engines, even when aided with turbochargers and stock efficiency aids, have a mechanical efficiency of about 20%. Most internal combustion engines waste about 36% of the energy in gasoline as heat lost to the cooling system and another 38% through the exhaust. The rest is lost to friction, about 6%."
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So let's assume a mechanical efficiency of 20 percent. Engine output is therefore 11.4 kW (15.29 hp) at 60 mph. Much lower than my previous estimate. An electric car can achieve this without heat losses, and therefore would consume no more energy than it puts out. The US Dept. of Energy has published the power consumption of the EV-1 at 60 mph as 9.79 kW, which implies a mechanical load about 14 percent lower than that of the Kia Rio. This might be achieved with the very low aerodynamic drag coefficient, or better drive train efficiency. Regenerative braking probably would not have been significant for long trips at highway speed. Maybe.

Numbers feel better now. Must sleeeeeep.....

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