I think what they need to do is make an instant on/off engine mated to an instant on/off transmission.
Right now, even when you are going down hill, the car slows down because of transmission friction, and you end up hitting the accelerator to maintain your speed.
If it's instant on/off, they can afford to let the car go in neutral when the driver isn't accelerating, so you won't use up fuel fighting the transmission. Same goes for instant on/off engine. If it can be turned on instantly, there is no reason to keep the engine running when you are just rolling along
At highway speeds, it's mostly aerodynamics, so it won't buy you that much.
Check out this entry in the Tesla Motors blog: http://www.teslamotors.com/blog4/?p=70
It talks about the power required to maintain a certain speed and what's responsible for it.
The Tesla Roadster uses ~ 230Wh/mile to cruise at 55mph. What is that in equivalent mpg? Gas has 34MH/liter, which is 35800 Wh/gallon. For reference, that gives 35800/230=155 mpg.
With the given frontal area and Cd of that Mustang, it takes 140Wh/mile to overcome aerodynamic drag only. Let's assume they have a magic, loss-free power train. That leaves the tire drag, which should be about the same as the Tesla since they are both high-performance cars and probably weighs the same given the Tesla is dragging around all the batteries. The Tesla plot shows tire drag to be ~60Wh/mile, which adds up to a theoretical minimum of 200Wh/mile, which is 180mpg.
A more realistic assumption is that the Mustang power train (they only talk about engine so I assume it has a standard transmission) is no more efficient than the Tesla's, which requires a further 75Wh/mile. This brings us to 275Wh/mile, which is 130mpg.
To reach 110mpg, the engine would thus need a thermodynamic efficiency of 85%. This is more than twice the efficiency of diesel engines at ~40%.
well they kinda do that with the prius, the motor will start up when needed using the high speed wheel motor which can start the engine much more easily than a starter motor.
I think the simpler route is to just use an electric motor for the power directly mated to the wheels. No drivetrain, it's only used when you need power (no idling) and it's instant on/off....
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I think what they need to do is make an instant on/off engine mated to an instant on/off transmission.
Right now, even when you are going down hill, the car slows down because of transmission friction, and you end up hitting the accelerator to maintain your speed.
If it's instant on/off, they can afford to let the car go in neutral when the driver isn't accelerating, so you won't use up fuel fighting the transmission. Same goes for instant on/off engine. If it can be turned on instantly, there is no reason to keep the engine running when you are just rolling along
At highway speeds, it's mostly aerodynamics, so it won't buy you that much.
Check out this entry in the Tesla Motors blog: http://www.teslamotors.com/blog4/?p=70 It talks about the power required to maintain a certain speed and what's responsible for it.
The Tesla Roadster uses ~ 230Wh/mile to cruise at 55mph. What is that in equivalent mpg? Gas has 34MH/liter, which is 35800 Wh/gallon. For reference, that gives 35800/230=155 mpg.
With the given frontal area and Cd of that Mustang, it takes 140Wh/mile to overcome aerodynamic drag only. Let's assume they have a magic, loss-free power train. That leaves the tire drag, which should be about the same as the Tesla since they are both high-performance cars and probably weighs the same given the Tesla is dragging around all the batteries. The Tesla plot shows tire drag to be ~60Wh/mile, which adds up to a theoretical minimum of 200Wh/mile, which is 180mpg.
A more realistic assumption is that the Mustang power train (they only talk about engine so I assume it has a standard transmission) is no more efficient than the Tesla's, which requires a further 75Wh/mile. This brings us to 275Wh/mile, which is 130mpg.
To reach 110mpg, the engine would thus need a thermodynamic efficiency of 85%. This is more than twice the efficiency of diesel engines at ~40%.
It can't work.
well they kinda do that with the prius, the motor will start up when needed using the high speed wheel motor which can start the engine much more easily than a starter motor.
I think the simpler route is to just use an electric motor for the power directly mated to the wheels. No drivetrain, it's only used when you need power (no idling) and it's instant on/off....