Combined GPS and Mini-Scanner data

Hi folks,

I've recently combined GPS NEMA with Graham Davies Mini-Scanner data on a trip from Huntsville AL to Knoxville TN. This allows using GPS altitude along with the fuel consumption data calculated from the Graham scanner:



The same data in metric:



This first detailed chart shows the impact of coming to a stop. To handle the problem of dividing 'distance/fuel' with the engine off, I carried forward the last MPG value. The Prius MFD shows "99.9" in such cases although math tells us it should be a very large number. The draw back with this approach, the carry forward of a lower 'distance/fuel' rate, is it suppresses some of the effect of ICE off. This said, it also shows the challenge of coming to a complete stop with the impact of acceleration on the average MPG:



Regenerative braking is better than ordinary brakes but it is not terribly efficient. Many efficient drivers learn quickly to minimize energy regeneration.

In contrast, hills do a much better job of energy preservation. Climbing the hill burns more fuel but it substantially increases the potential energy and pays it back on the downslope:



One interesting aspect is the GPS ground plot led to finding a more Prius friendly route headed east from Huntsville:


Yesterday I tested the original and new route from south Huntsville to Gurely AL and found they took the same duration, 30 minutes, but:

• 21.6 mi, 58.6 MPG - original route
• 15.6 mi, 61.3 MPG - new route

This repeats the pattern of finding direct, Prius routes at slower speeds but identical elapsed times. Route planning pays dividends.

My inexpensive, $50, GPS has a lot of altitude wander in the first minute. But after the first minute, it appears to be accurate enough for my studies. I'm working on a program to read both the GPS and Graham scanner data into a single, comma delimited text file for future studies.

Bob Wilson