My premise is that running a downsized engine at peak VE, producing just enough HP to maintain highway speed, is where you maximise fuel consumption.
The penalty of running a downsized engine at peak VE, is less available power. The penalty of having a bigger engine, is running off peak VE and BSFC, and more weight. The penalty of adding a turbo to regain power is the much higher BSFC under high rpm/load (with current technology). The penalty of a hybrid system (as a power adder) is the cost and weight of the motor/battery. Diesels have low rpm torque, lean burn/stratified charge, turbos...but expensive after treatment, to the point where it doesn't pay for itself vs a gas engine for several years.
If consumers wanted lowest fuel consumption, they would buy sub compact cars with 1L engines. 50% of new vehicle sales are full sized trucks. most people value style and status over fuel/energy consumption. And honestly, keeping a car for 10 years costs much less than buying a new car every three years...regardless of how much more efficient it is (plus manufacturing process).
diesels and gas ice will surpass 50 mpg very shortly. imo, EV are a real solution to lower life cycle energy usage. iirc GE recently announced a new battery chemistry that will undersell and outperform lithium by a significant margin. I believe they said a couple years to market. Even the projected cost efficiency of lithium batteries will reduce cost $2500 in the next few years (for the Volt's 16.5 kW battery).
The Spark EV, for instance, is currently a $2,600 premium over an equivalently equipped Spark gas car (with Ontario rebates). A cheaper battery and electronics will make the gas powertrain redundant in many locations. Same initial cost outlay, lower operating and maintenance costs. Instant torque, silent, smooth.
Power Japan has invented carbon/carbon batteries. cheap, power dense, stable.
Dual-Carbon Battery: Same Energy Density, Safer, Longer Life Than Lithium-Ion, Says Power Japan Plus
apparently they don't believe that "carbon containing" is the definition of "organic". Wait until they start using carbon nanotubes
