[user removed]

Originally Posted by RobertSmalls

It bothers me every time I hear that line in the railroad ads. No, it can't. I bet a train uses many gallons of fuel just to get up to speed. If you have to move one ton of freight, use a truck. The train will be lucky if it makes it a mile on one gallon.

The railroad ads also neglect to mention the 120mi/(ton-gallon) figure for a fully loaded tractor trailer, and that if you use rail, the load will travel more miles overall, and you'll need a truck to finish the job.

Railroads save fuel, and we should use them more. But their ads paint an incomplete picture.

And a train is actually pretty aerodynamic. It's like a paceline of 100 tractor trailers drafting each other very close. Actually, it's more like a train, with a negligible frontal area, an enormous wetted area, and unfortunate gaps between each rail car.


Anyway, I can tell you my hybrid gets its best fuel economy when the electric system is inactive. Sure, while accelerating, I could use the electric motor to shift the engine to a more efficient operating regime, but I'd have to pay the battery back at an efficiency less than 100%. When, as dcb points out in the first post, 90% of peak BSFC is easily achievable, it really doesn't pay to use the electric.

Given a series hybrid with a certain size engine and electric motor in a certain chassis, you could improve its highway efficiency by making it a parallel hybrid, without exception. Instead of the Volt running its ICE to run a generator to run a motor to drive the wheels, just use the ICE to drive the wheels once battery charge runs out.

A parallel hybrid with a large electric motor could be designed to cruise on the highway near peak BSFC, using the ICE for cruising and the electric for accelerating.

I expect my next car to be a plug-in parallel hybrid with a tiny gas engine and enough electric range to handle my commute.

I read somewhere that the peak BSFC on the lean burn insight motor was close to 49%.

regards
Mech