Switching to electric is a massive increase in conversion efficiency, from something like 20% to around 90%. But the current battery systems are limited, despite massive research.
As far as the cost, electricity to charge them is only cheaper than gas until there is a large enough number of EVs for the gasoline tax revenue to start dropping.
One option is to go with an aluminum-air battery, but it's a non-rechargable primary cell. But at 1300 Wh/kg(and a lot higher theoretically), compared to LiIon's 100-265 Wh/kg, it can provide range enough for anyone.
Actually conversion efficiency is closer to 70%
Round trip efficiency on a battery is 80-90% (depending, high performance lithium batterie far cars are actually closer to the 80% number due to internal resistance losses on peak discharge, also the faster you discharge or charge the lower the efficiency)
A motor is 90-95% or so
Also, that electricity came from somewhere, so let's say its the highest thermal efficiency type of power plant, a ICCGT (integrated combined cycle gas turbine), at about 45-50%
Total cycle is then about 30-35%
High performance gasoline engine is about 25%
So an electric is at most about 1.2-1.4x as efficient whole cycle as a gas engine, and about the same as a diesel.
The issue with aluminum/air is discharge rate, as surface effects with air cells tend to cause limitations in power performance
Also, on the cost issue, its not necessarily cheaper, its actually either a cost shift (increased vehicle cost vs identical specs at lower recurring cost) or due to apples and oranges--EVs tend to be more efficient in their utilization of energy (better aero, regenerative braking, lower parasitic loads), and a comparison of a hybrid vehicle (especially a diesel hybrid) with identical output specs and payload specs actually shows the hybrid being roughly the same in terms of total cycle efficiency as a pure EV, and with a lower carbon footprint, as diesel or gasoline is lower carbon per unit energy than the average electrical power source (50% coal, 30% NG, 20% nuclear and renewables)
A quote I used before:
If all I wanted was a 400+hp sedan, and all I cared about was carbon footprint, I wouldn't get a Tesla, I'd get a CTS-V, M5, or Merecedes.
oddly, just about every Ducati rider I've ever met has been a *expletive deleted*... I have no idea why those bikes attract those people...
Gee...didn't know you felt that way about me! (I've owned 3) :)