Originally posted 31 Oct 2006:
I've been ruminating on what a (much) more efficient automobile would look like, and here are some random thoughts:
We need to use a smaller motor, while still getting enough power out of it, so maybe 1.0-1.3L four cylinder (or maybe even smaller?), with a small turbo? It would also have variable valves, to maximize the low RPM torque (fewer valves with shorter duration, IIANM), and then more valves for longer duration, etc. at higher RPM's. This same mechanism could be used to shut down two of the four cylinders at idle, and in low-demand situations, and then all four cylinders could seamlessly be brought back into operation as more power is demanded. It would not be too hard to have the entire engine be shut off when sitting still.
The transmission would have 6 to 8 speeds; again to help utilize the available power. I would want a manual transmission, but the clutch would be used only in first (or second) gear for getting rolling. Thereafter, gearshifts should be handled like they are in an Formula 1 car: shift paddles under the steering wheel to shift up or down, with the ignition computer "blipping" the engine momentarily while the transmission shifts. In Formula 1 cars, this happens at a mere 19,000RPM, with a 7 speed transmission -- so I can't see why it couldn't be done at 2,000-6,000RPM?
This scheme would allow a direct drive situation with virtually no slippage once the car is rolling. Also, the throwout bearing in the clutch should be well lubricated for coasting. I think that a manual transmission has much better control, for driving in typical New England winter conditions, for example.
All the aerodynamics should be improved to a point where the drag is reasonably close to ideal, without becoming impractical. The underside should be included in this, and also low rolling resistance tires are also key. A while back, I remember seeing tweaks like partially recessed side mirrors, that reduced the aero drag -- this seems like a reasonable thing to do, too.
Here' are newer blog entries that I have written on this subject:
Cars to emulate and study
Aerodynamic modifications to save gasoline
More ways for auto makers to build more efficient vehicles
"Eyes forward" video mirrors on my Scion xA