Hi Bill

Is your Escape a hybrid? The reason I ask is the Atkinson 2.3L has very little low RPM torque compared to the standard 2.3L or V6 engine in the Escape. This causes the FEH to reach 100% max engine load and electrical motor assist at a very low RPM. With straight gas, that little more power makes a big difference in keeping under 100% engine load during acceleration. If you can keep engine load down and avoid draining the battery state of charge with assist, you can get over 70mpg on straight gas in the FEH. Using the best hypermiling skills I know, I could not hit 50mpg on the same flat roads on E10. Rolling hills at the '07 MPG Challenge I managed 61.8mpg on E10 with perfect condition in a FWD FEH.

I've compared straight gas and E10 since '05 many times till E10 was mandated ~ May '08 in my '05 FEH. The results were constantly the same with mileage drops with E10. My oldest Son (MIT Grad) comes down from the cold weather and drives my '05 FEH to Miami and all over Florida for vacation every few months and this last time he reported lack of power above 70mph. I checked the SGII and found 6,000 rpm max and 80mph max and thought the E10 was giving him problems at those speeds. Sure enough when I took it out on I-95 at 70mph and over, I was having a hard time keeping the engine load under 100% and electrical assist on E10 at those speeds. Never had that problem on straight gas.

GaryG

 

I've found by mistakenly putting premium 93 octane in my tank, it was almost as bad a E10 for a MPG drop. Ford recommends 87 octane in all FEH/MMH and I find I get the best mileage with it. Ford also recommends using no additives and can void your warranty if you do in the '09 FEH/MMH according to the owners manual.

GaryG

 

I had the same experience.

Through a local grocery chain discount deal I was able to get 45 cents off per gallon up to 20 gallons. I took my Mustang (which requires premium) and the FEH to the same pump. I filled the Mustang and FEH for really cheap but paid for it later that same day when I went out on the Interstate for a 250 mile round trip. This trip is usually good for about 31-32MPG (at PSL). The best we could do was 27-28MPG (at PSL). That's the last time I'll put premium in the FEH. Even if I'm getting a great deal on the it.

The old MG uses standard gas so it will be the fill-up buddy next time we cash in the gas perks.

On a side note, the Mustang seems to get a little better mileage when I use premium over the middle grade. Granted, I have to pull back the timing a bit with middle grade to keep detonation at bay. It's just not worth the hastle when I factor in all the variables in my head so I just use premium and drive it less these days. Besides I love driving the FEH and playing the FE game.

 

Yes, my Escape is a hybrid & AWD.

The octane rating should make no difference in engine performance. In Wyoming they sell 85 octane. Since the altitude is above 5,000 feet the physics of the engine pressures means that an engine that must have 87 at sea level will run fine above about 5,000' with 85.

Octane rating only tells you its resistance to detonation but nothing else. Energy wise it is as good as 87 or 85. Any ethanol in your gas means you have less energy available so the engine should not run as well.

I understand the difference between the Atkinson & Otto cycles. My point about the electric machines, since they have to supplement the ICE, is that the way they increase power is to raise rpm (watch the engine on speed control). And so the engine ups its rpm to provide that with the associated loss of energy to higher internal friction at higher rpms.

Over the years I have put the least expensive gas I can find in my cars and tracked the fuel mileage: 71 Plymouth Duster (225 slant 6) - 164,000; 92 GMC Suburban (350 V8) - 366,000 & going strong; 01 Mustang Cobra (4.6L DOHC)- 257,000 & going strong.

I run the Mustang (4.6L DOHC & will it pull!!) on a 50-50 mixture of 93 & 85 octane up here in Wyoming (equivalent octane is 88). I run 85 in the Suburban. Using an octane above that which is needed by the engine design is unnecessary.

I track both tank to tank and long term mileage. My Escape Hybrid has 41,000 on it. I find that when I have a really good tank mileage that it gets taken back within a tank or two, so if I can't show about the same mileage over 1-2,000 miles I don't count it.