Just a couple of questions:

• What is your round trip best?
• How did you measure 152 mpg?

A round trip makes sure other sources of energy such as potential energy are not involved and the battery can be good for a mile. As a general rule, the first mile should be dropped to normalize the battery state of charge.

Were you using one of Ken's super scanners? Normally, the MFD pegs at 99.9 MPG.

As a suggestion, you might try a circular route using both your 20-28 P&G as well as the equivalent, steady speed. I've been doing some work in this area:



The first set of charts were used to measure the equivalent steady-state speed. It was also used to make sure the protocol was reproducible. One of the classic problems with most P&G protocols are imprecise instructions. In this case, the glide uses "N", a completely energy neutral glide. The pulse used cruise control "resume speed," which ensures a reproducible acceleration.




The above set of charts show the results of 25-43 PnG. The data suggests PnG is about 11% more efficient than the equivalent steady-state speed. However, this is also the maximum, speed difference possible using cruise control and staying in the ICE-off, "N" glide range.

The following charts show the data used for the above summary chart:




The following is an interesting chart from manually trying to stay at 18 mph. What is curious is the ICE failed to cycle off, initially. This could have been S-3 mode. Later, the normal ICE on/off cycling resumed. Regardless, the energy consumed was pretty good, 255 J/m.


So I tried using PnG that gave the same block speed, 18 mph, and found the energy consumed was higher, 299 J/m versus 255 J/m. Steady-state required 17% less energy than the equivalent PnG.

Near as I can tell, the optimum distance speed is ~18 mph within a speed range of 16-21 mph. So far, my limited attempts to PnG around this speed have consumed more energy than the steady-speed mode.

So why is this important?

It looks like my Prius gets about 15,000 J/gram of ICE shaft energy and it takes 255 J to move one meter. One gram of gas should move my NHW11, 2003 Prius about 58.8 meters. With ~2,659 grams/gallon and 11.9 gallons per Prius tank, one tank should give 1,860,555 meters or about 1,162 miles. This isn't bad but I would prefer more margin.

Bob Wilson

Operation Iraqi Oil Freedom:

Automatic, stock, project car.

My other 1500 cc car:

Automatic, stock, backup car.
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