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%.
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.