When Consumer Reports tested out the Hymotion L5 plug-in Toyota Prius conversion earlier this year, they weren't overwhelmed with the results. Sure, the mileage they observed was boosted to about 67 mpg over the first 35 miles of the drive, but that didn't match the claims of 100 mpg (or more) that Hymotion and A123 Systems make about their product.
To be fair to Hymotion, their qualifies mileage talk about their plug-in Prius MPG "that can achieve up to 100 mpg for 30-40 miles" this way:
Hymotion PHEV fuel economy is based on independent testing performed at Argonne National Labs and Idaho National Labs. Actual mileage will vary based on each individual's driving style, route, traffic, climate conditions, terrain and other factors.
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