Hello,
I spent yesterday driving the "water trolley" in support of a bicycling event in SE Virginia. Overall, I delivered 120 gallons of water and 350 lbs of ice, leaving home at 5:30am and returning about 12 hours later. What a day!
The moment of truth came when it was time to refuel. I wanted to see the hit to fuel economy. I've calibrated my display to more accurately reflect average MPGs. Still, I thought this was a little optimistic:
My average speed is so low because of the time spent with the engine off and ignition on so I could charge my phone at drop-off points. The phone spent much of its day in GPS/Navigation mode, which sucks the battery. Most of my driving was between 45-70 mph, depending on the road.
I did the math and was surprised to see that my display is pretty accurate, or as accurate as it can be without the true ability to top-off the tank. In short, I drove 281 miles and added 11.2 gallons of fuel, which calculates to 25 mpg. That's fantastic when considering the heavy load and aerodynamic wall on the roof.
Scott