I think the weather has more to do with this than anything. The colder it is, the less mileage the batteries will be able to assist with. I was averaging over 30mpg in our 08 escape hybrid and now with northern cali weather in the 30-50 range most of the time, our mileage has dropped to 27mpg, or just over 10%. Wait till warmer weather and I'm sure these stories will disappear.

 

Absolutely. Average trip duration and type of driving will have a large impact, as well.

I have an 07 camry hybrid that got around 36mpg average when I was commuting 30 miles a day. Right now, my round trip is about 8 miles. By the time it gets warm enough to shut the ICE off, I am at my destination. My average has gone down to around 26 mpg, but that is expected.


My 08 Escape hybrid is pretty consistently around 32 mpg. The largest impact here is summer driving. Since the engine must be running for the AC to work with the belt driven AC, summer average goes down to about 27.

In both cases, however, EPA claimed mileage is fairly close to what I am seeing with both vehicles. I understand that real world conditions vary greatly from the dyno simulated EPA mileage test, so I wonder if the test procedure has changed from when either of my vehicles was produced until now.

I would say that route planning can have as large of an impact on observed mileage as driving style. People who jump in a hybrid and expect EPA mileage when they drive the same way they did their F-150 may not get the results they expected.

 

Poor mileage in cold weather is not limited to hybrids. Hybrid owners just tend to obsess more over fuel economy.