See, I knew you were a club member!

The MPG vs MPH graph is derived from the vehicle drag. Knowing the rolling and aerodynamic drag, we can calculate exactly how much power is needed maintain any speed. But the Prius needs about 500 watts of power just sitting in the driveway for things like the headlights and control computers, the 'fixed overhead.'

As the Prius speed gets slower and slower, this fixed overhead becomes a larger and larger proportion of the energy needed. Eventually, at a slow enough speed, your mileage is worse than if you ran just a little bit faster. What this curve does is let us calculate the maximum distance or highest MPG speed. That runs in the 18-20 mph range.

If I wanted to run a marathon on a single tank, I would drive the car at a steady speed of 19 mph. For maximum distance, I would do it in Leadville CO in the middle of August on over inflated tires through the parking lot at the Colorado School of Mines. For a solo effort, I would rent a room and drive when head lights are not required. At night, I would plug in a block heater and use heat lamps on the bottom of the engine. Each day should cover about 280 miles so it should take about 4-5 days to cover the 1,100 miles expected and not drive on any rain days. An NHW20 should add a couple of days.

The car would also have over inflated tires, zero-toe front and rear alignment, barely filled oil, and no excess weight beyond water and 'comfort food.' The radiator block would be replaced by duct tape as would the underside gaps. The wheels would have 'moon covers' made from light weight plastic.

The week before I would work out the logistics with the School of Mines to use their property and restrooms. I would also use a small, rented generator, space heater and clock to measure the energy content of the local gasolines. For good measure, I would bring 15 gallons of the best straight gas I've found in Huntsville.

Bob Wilson

 

Congrats!!