The reason I asked about the speed is knowing the steady-state MPG performance at any given speed allows us to quantify to what extent 'skill' replaced just driving in the 'sweet spot.' For example, I spent a Saturday morning last spring gathering the data for this Prius NHW11 chart:
Knowing the average endurance speed in an NHW20 Prius was ~35 miles per hour, I can look on my chart at 35 miles per hour and see the expected MPG should approach 75 MPG. The Prius mileage team achieved 110 MPG, a 35 MPG advantage.
Now some of those miles came from:
- smoothy, high pressure tires, 60 psi
- Type WS transaxle oil used in NHW20, not Type T in NHW11
- 0W20 engine oil at 3/4 between E and F, not 5W30 at 3/4 between E and F
These mechanical and maintenance differences don't require operator skill and pretty much work 24x7. Missing is any quantification of the effects of each of these changes. But a funny thing happens if the average speed is not 35 miles per hour but say 30 miles per hour.
At an average speed of 30 miles per hour, the Prius MPG difference between last year's test and the chart drops to 10-15 MPG. This is a less impressive improvement and well within the capabilities of the mechanical and maintenance differences.
I do not have MPG vs miles per hour mapping for speeds under 31 miles per hour. But soon enough, I will and with it, I should be able to find the maximum MPG, steady-state cruise speed of an NHW11 Prius and hopefully document the effects of mechanical and maintenance changes. Then we can quantify "operator skill" versus the base capabilities of the vehicle.
Anyone who goes over 1,000 miles / 1,400 km on a single tank has done good. Exceeding 100 MPG, even half of that for a sustained period of time is good. But without the vehicle performance data, it is really hard to understand what part skill played in the achievement. Worse, without quantifing what different maintenance actions achieve, we don't have a map for others to follow.
Bob Wilson