We like sheep... on the ECO Dashboard

Yeah, we know the feeling. We went to dinner at a friend's home about 35 miles away on a rainy night at the beginning of November. We usually plug in the car there, but I did not feeling like slogging through the rain to string a cord across their lawn to their exterior outlet. And so we ended up using about 3/4 gallon of gas for the 70-mile round-trip from home.

As of tonight (end of month) our Eco-Dashboard has all our sheep, rainbow, clouds, pine trees, oranges, and tulips. But our fuel use for the month is 599 mpg and that puts us in 166th place -- not in the top 100 of the "Fuel Consumption" list. Even so, our "ECO Driving Score" places our "Bear-Mobile" at 88th in that list.

What I find interesting is that the Prime at the bottom of the "Fuel Consumption" list -- "Prius Prime9221" -- achieved 999.9 mpg (i.e. all-electric) on only 20.92 miles of driving. (The Prime rated first -- "Prius Prime7195" -- achieved 999.9 mpg on 1583.85 miles.) The implication is that only 100 of the Primes were driven for more than 20.92 miles in all electric mode using no gasoline during the month, and that the vast, vast majority of Primes are being driven in HV mode using gasoline at least part of the time.

What this does not tell is whether those Primes were being operated in HV mode 1) because of distance driven (as in my case) or 2) because of not having a place to plug-in at some point during the month, or 3) because the owners elected to use HV rather than bothering to plug-in to charge.

Once we get beyond the novelty of the Prime as a PHEV and our desire to understand how far we can push the envelope of all-EV driving, we each settle into our own different patterns of using our Primes as our own personal automobiles. As Margaret Mead once said: "Always remember that you are absolutely unique. Just like everyone else."

 

Ah, the wonders of statistical mathematics.

The sheep and their companions were all happily on our ECO Dashboard heading into Christmas. Our Prime was among those shown in 1st place for fuel economy (999.9 mpg +) and the 412 miles we'd driven put us somewhere in the middle of the top one hundred 1st place Primes as shown in the ECO Dashboard list.

Then, on Christmas day, we traveled about 72 miles round-trip to the home of some good friends who were hosting Christmas dinner. We were able to drive about 27 miles in EV mode on the way there, then the rest using HV. We were able to plug in the 120v charger and bring the Prime back to full charge before heading home. And, we again did about 27 miles on EV and 9 miles on HV, only this time the 9 miles were in the middle of the trip on the Interstate at 60mph highway speed.

The Prime reported our fuel efficiency for the trip at 145 mpg which equates to about a half gallon of gas (72 mi / 145 mpg = 0.497 g). However, that brought our month-to-day mileage down to less than 999.9 miles per gallon for the 484 miles we'd then driven since December 1st. (484 miles / 0.497 g = 973.8 mpg). And that was enough to drop our Prime off of the top 100 list and put it in 121st place.

However, in the three days since Christmas, we've made several shorter trips in EV mode, bringing our total month-to-date driving to 617 miles. And that raises our mileage above the magic 999.9 mpg (617 / 0.497 g = 1241.4 mpg) and pops us back on the list of 1st place Primes in about the 11th position.

(Of course, no one can beat LePrimeSnail at 1297.9 miles -- but he lives in Southern California were people spend most of their waking hours in their cars.)

I was not keeping track of each of the Primes on the top 100 list, but it's entirely possible that one or more of them sinned by using some small about of gasoline and, like us, were dropped off the list. This may contribute to our Prime re-appearing in 11th among the 1st place Primes after having been about 50th just before Christmas.

I am not sure if this is a morality tale, a tale of redemption, or merely a lesson in how statistics can produce unexpected results.

Sheep, sun, clouds, rainbow, pine trees, oranges, and tulips are all present as we head into 2019.

Hope you all had a very Merry Christmas and we wish you a very Happy New Year!