Of how I understand P&G, you speed up quick, kill the engine and coast in neutral and repeat the cycle to get your wanted average speed.
My question would be then, If speeding up quickly is more effective than speeding up slowly (max mpg while running) wouldn't speeding up fast to your target speed, and continue at that speed and EOC when you need to slow down/turn? Maybe I'm just not understanding how P&G actually works
Another look at a similar idea in engine design, the hit and miss engine. So my next question would be... what is more efficent, our standard style engine or one converted to be a hit and miss say at 1/4-1/2 load or even idle (engine on coasting?? lol)
Which is more fuel effecient? - SmokStak
Even if the hit and miss design isn't more efficent, a smaller engine typically consumes less power to maintain speed compaired to a larger engine. So I got thinking that it might be possible to drop 2 cylinders from running a an I4 engine once you are up to speed with some sort of similar design as a hit and miss but be user controllable and would have to take into account cutting the fuel injectors off for the 2 cylinders as well as a cam over-ride system to reduce the air pumping losses.
Just a small background on this, my uncle told me of a story of someone he knew years ago that modified a small car that had a I4 engine so that it was a I2 engine (removing the pistons and grinding the cam loabs maybe?). It had hardly any power (story stems from him having to help push it in loose sand). He claimed the driver was getting 60-70mpg and took well over a mile to get up to speed. I would suspect the driver probably drove slower aswell.
Same uncle talked of another guy that put a small 4 cy engine and put it into a full sized van which then became FWD with similar results but more like 30mpg. These numbers are just from memory (and his!) but I suspect they were real world storys, just the numbers could be off a bit.
Anyway, discuss what you think, examples are always interesting.