I won't go into too many detail, but recently I really had to kill about 1.5 hours at home, and had access to all of our cars (Focus, Avenger, and Sonic) as well as a brand new Escape (1.6t) from a relative. I was particularly interested because the Escape is we recentl test drove and are going back and forth on it as far as a potential next vehicle. Anyway, I decided to do as scientific of a mileage test as I could from someone without professional equipment.
There is a highway right near us, it is in a nearly rural type area, and there is very little traffic on it at all. From where I started the test , there is 1 turnaround (I did the test round trip to negate the effects of wind and elevation) and the total loop is almost 13 miles. I got the vehicle up to speed, reset the mileage guage, and then drove the loop. I took the readings at the same point (used a roadsign on the way back) before slowing down. The only stop was one time to turn around, and the gas was let off at the same point (a road sign for reference) and when getting back up to speed I used the resume button (or tab) on the cruise control. The vehicles were all 'warmed up' for a couple minutes before starting, and I let them sit for 3-5 minutes after each run to let the engine and tires cool slightly. I began the test with the car up to speed already so no acceleration to speed at the start of the test was needed.
The test conditions were a smooth highway road, 62 degrees, 92% humidity, a light wind (6mph according to the internet weather station) out of the SSW, and elevation is about 300 feet above sea level. Under such good conditions, and cruise controll set at pretty low speed (and not much elevation change at all along the route), I expected to handily beat the EPA numbers, it is just a matter of how much and at what speeds.
So here are the first grouping of the results:
2013 Ford Focus SE 6-speed auto, 2.0 (2500 miles on the car) EPA highway 38:
-at 45mph, rpms at 1700, 51.7 mpg for the loop (36% above highway rating)
-at 55mph, rpms at 2000, 46.2 mpg (21.5% above highway rating)
-at 65mph, rpms at 2400, 39.7 mpg (4.5% above highway rating)
2011 Dodge Avenger 6-speed auto, 3.6 (50,000+ miles on the car), EPA highway 29:
-at 45mph, 1150 rpms, 41.0 mpg (41.4% above highway rating)
-at 55mph, 1500 rpms, 36.2 mpg (24.8% above highway rating)
-at 65mph, 1700 rpms, 30.5 mpg (5.2% above highway rating)
2013 Ford Escape FWD, 6-speed auto, 1.6t (2000 miles on the car), EPA highway 33:
-at 45mph, no rpm reading taken, 44.9 mpg ( 36.1% above highway rating)
-at 55mph, 36.5 mpg (10.6 above highway rating)
-at 65mph, 31.7 mph (-3.9%, BELOW highway rating)
The Sonic numbers I will post later (the paper I recorded them on is in the car, and the car is not at home now) but I can tell you they are similar in percentage terms to the Escape....the drop-off from 45 to 55 to 65 is much more drastic in the Sonic (just like the Escape) than it is in the Avenger and the Focus.
While not scientific, this does support something I have heard other people talk about.....the modern Turbo engines do well in EPA testing where highway mileage is kept at a lower speed for most of the test, but when they are 'under load' at higher speeds (like most of us drive) they will be more likely to underperform the EPA results than non-turbo engines.