I just got back from my first long trip (300 miles). 90% of the trip was on relatively flat highway. I averaged 36.6 MPG.
Now my normal driving average is ~ 31 MPG (around home, to/from work, etc.). I assume for this survey you want me to register the 31 (which I did) and not the 36.6 which is a one-time deviation from my normal driving habits; correct?
Do you think the EPA is smart enough to factor in both the car's basic fuel efficiency and the driver demographics?
I am thinking that maybe the EPA measures the Cube's fuel economy on some sort of dynamometer then applies driver population/demographics.
For example; the Cube's treadmill calculation may be 55MPG (front roller friction only; no hills or wind resistance). For city driving they then use a set of driver density calculations; e.g., 50% of the population drives in dense suburbs with an average trip of 7 miles, a stop every .5 miles on rolling terrain, 30% drive an average trip of 15 miles, stops every 2 miles on flat roads, etc. Of course these averages should be based on just the countries that Nissan is selling the Cube and the sales volume for each of those countries.
This survey should be reflecting only the demographics of the people who have posted; not necessarily the global average.
Thats a very good question, I have seen some very educated people discuss this topic. Some of the easy factors is you must fill up at the same pump same time of day and such to ensure as close to exact volume control.
My Honda Fit is rated at 34Mpg Hwy and I regularly exceed that and have bested it at 44Mpg several times. So that one is off in my demographic huge and half of those miles are city. I know they use a complicated algorithym and a bunch of new math to get there but I am usually right on target in the Cube so I quit tracking.
Very complicated calculation indeed. Including AC use in the new EPA calculation should bring the estimate closer to reality. When I hit 36.6 on my recent 300 mile trip, it was during a cool day and I had the AC off. I took shorter (~30 mile) highway trips before, but with the AC on, I averaged closer to 34 MPG. So a better calculation would include mixes of terrain variables (rural, suburban, urban, hilly/level, etc) and month-to-month temperature variations that would affect AC use and fuel combustion efficiency.
They also indicate the new calculation includes faster acceleration and higher cruising speed variables from the numbers established 40 years ago. What took them so long.