Try this:

At 70 mph the engine consumes 250gm/KwHr

You can Pulse, and burn fuel at 210,

and then you'll need to Glide. the engine burns more fuel at 2,500 rpm than it does at 900, say 1.1 vs 0.4

So, if it you have 50 litres of fuel to burn, at the steady cruise rate of consumption (250 nad 0.85 sg) thats 170KwHr

running at the 210 level saves you 8 litres fuel, but some of that is used to keep the engine turning over whilst gliding. The gliding time is likely to be say 4 hours? thats 1.6 out of the 8, leaving you with 6.4 litres still in the tank to go someplace with, and to add to your mpg's.

Did that add up? - cheers

Thanks again! Well, it still didn't quite add up.

What I miss is that when you pulse at 210 g/kWh, you are using 16% less fuel per kWh, but your using more kW during the pulse (maybe twice as many?), so you still are using more fuel during the pulse. I don't think you can directly apply that 16% to a 50 liter tank and save 8 liters.

How about this, using shizzler's graph above:

Assume that at cruise, 2500 RPM, 73 mph, I use 265 g/kWh, and generate about 65 nm torque (interpolating these values from the graph). Doing some conversions, 65 nm = 48 lb-ft which at 2500 RPM gives 22.8 hp or 17.0 kW.

So I'm using 17 kW to cruise, and every hour I use 17*265 = 4.5 kg/hr = 5.3 l/hr = 1.4 gallons/hr. Since I'm going 73 mph, I'm getting 73/1.4 = 52.1 mpg.

This seems like a reasonable result. I can go 886 miles on a 17 gallon tank, and it takes 12.1 hours to use up the tank.

Now, imagine that I'm using P & G for the whole tank. Here are some assumptions:

- same average speed, 73 mph

- pulse and glide time evenly split: 1/2 of the time spend pulsing, 1/2 gliding (don't know how accurate this is).

- when pulsing, I use 210 g/kWh

- when pulsing, I generate 150 nm torque, or 40 kW.

- when gliding, I use fuel at 0.4 l/hr.

With these assumptions, I use fuel at these rates:

- during glide: half the time is 12.1 hr/2 * 0.4 l/hr = 2.4 liters

- during pulse: half the time is 12.1 hr/2 * 40 kW * 210 g/kWh/1000 * 0.85 = 59.8 liters

So I've used 2.4 + 59.8 = 62.2 liters = 16.4 gallons to go the same 886 miles (since I averaged the same speed).

I did get better mileage, 54.0 mpg instead of 52.1 mpg.

It seems likely that the pulse time would be shorter than the glide time. Let's say the time is split 40/60 pulse/glide, instead of the 50/50 above. Working through the same gyrations, I'd calculate now 65.6 mpg.

A scangauge would probably help to nail down those fuel consumption rates to make a more accurate calculation, but in any case, your actual results seem to say that this really can be done.

Fantastic!