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The extra weight of a battery and electric drive train means at least part of the fuel efficiency is compensated, hybrids typically weigh 200 Kg more than their

The extra weight of a battery and electric drive train means at least part of the fuel efficiency is compensated, hybrids typically weigh 200 Kg more than their ICE counterparts. There's another measure that would have saved everyone a lot of money and emissions: better aerodynamics. Car makers have been building terrible designs for decades because gasoline was cheap, but we know they could do much better. A car with good aerodynamics (like the Prius by the way, or the Hyundai Ioniq) saves enough fuel to not need a hybrid drive train.

kennywinker 7y ago
At what speeds? I find it hard to believe aerodynamics would make that much of a difference for your average rush-hour commute, but maybe that’s my urban bias showing.
- lazyjones 7y ago
  I'm not sure my simplified math is valid, but for example the F-150 frame with Cd = 0.36 and 2.9m² frontal area vs. the Prius with Cd = 0.25 and 2.17m² frontal area would use theoretical ~55 Wh/Km more at constant 80 Km/h (~50 mph) just due to air resistance (excluding ground friction etc.). Assuming a total efficiency of 20% of a gasoline engine and 1 litre of gasoline containing 8.8 KWh of energy, this means approx. 3 litres per 100 Km more gasoline, just due to aerodynamics (not weight etc.). For a less extreme comparison, the (2006) Mini Cooper S vs. the Prius I get 13.45 Wh/Km difference, meaning 0.7 litres per 100 Km (at constant 80 Km/h, only due to air resistance). Perhaps one day it'll be possible to attach the self-driving car to the back of the car in front on boring commutes to get rid of this factor. ;-)
xallace 7y ago
Obvious improvements for traffic in terms of aerodynamics: * Get rid of side mirrors (legislation is the biggest challenge here) * Adaptive body elements * Less powered cars (less powered >> less need for removing the heat >> better aerodynamics) * disincentivize SUVs
- Zanni 7y ago
  I hope you mean "replace the side mirrors." People are bad enough about head checks as it is. And replace them with what? Sensors? Cameras?

kennywinker 7y ago

At what speeds? I find it hard to believe aerodynamics would make that much of a difference for your average rush-hour commute, but maybe that’s my urban bias showing.

lazyjones 7y ago
I'm not sure my simplified math is valid, but for example the F-150 frame with Cd = 0.36 and 2.9m² frontal area vs. the Prius with Cd = 0.25 and 2.17m² frontal area would use theoretical ~55 Wh/Km more at constant 80 Km/h (~50 mph) just due to air resistance (excluding ground friction etc.). Assuming a total efficiency of 20% of a gasoline engine and 1 litre of gasoline containing 8.8 KWh of energy, this means approx. 3 litres per 100 Km more gasoline, just due to aerodynamics (not weight etc.). For a less extreme comparison, the (2006) Mini Cooper S vs. the Prius I get 13.45 Wh/Km difference, meaning 0.7 litres per 100 Km (at constant 80 Km/h, only due to air resistance). Perhaps one day it'll be possible to attach the self-driving car to the back of the car in front on boring commutes to get rid of this factor. ;-)

xallace 7y ago

Obvious improvements for traffic in terms of aerodynamics: * Get rid of side mirrors (legislation is the biggest challenge here) * Adaptive body elements * Less powered cars (less powered >> less need for removing the heat >> better aerodynamics) * disincentivize SUVs

Zanni 7y ago
I hope you mean "replace the side mirrors." People are bad enough about head checks as it is. And replace them with what? Sensors? Cameras?