Hi Jeffrey,

There is a vehicle specific componet to these. Although many are to a greater or lessor mode shared, there is one biggie for the Prius pilot.
Stop and go taffic usually means lower speeds putting the Prius in a better fuel efficiency range. The average EPA speed for City is about 20 mph and both models of Prius get higher MPG in City operation compared to the Highway. The large Prius MG2 and battery pack handles regenerative braking and electric only modes at slow speed, City driving. This is true as long as the speeds are 38 mph and below, a 4 mph guard band away from 42 mph.

Due to the transition speed of 42 mph, Prius drivers should avoid 39-50 mph. This is unique to the Prius and has to do with a transition between two types of control laws. This also means that a Prius going at highway speeds is OK but they need to stay there as long as possible. My NHW11 Prius is rated at 45 MPG in the EPA Highway test which has a speed of 48 mph. But at 51-65 MPH, I regularly get 55 MPG.

Both vehicles begin to suffer significant mileage hits starting at 65 mph air speed. Head and side winds require a lower highway speed and tail winds allow a little higher.

Bob Wilson

Operation Iraqi Oil Freedom:

Automatic, stock, project car.

My other 1500 cc car:

Automatic, stock, backup car.
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