I agree on the MPG, but in my experience 5 to 6 MPG is quite low. I don't disagree with the MPG split in general, but it can be very hard to pinpoint the real difference. My experience is that a mostly fully loaded V10 gets about 9mpg. There are 100 factors, like speed, the driver, and the drive cycle. Exhaust manifold leaks will slaughter the MPG on a gas engine, and they are common on V10s but not on the gas GM motors. Plus asking someone abut MPG is a mess. Half the people lie to make their point, half the people use an inaccurate method to determine the MPG, and the last half don't keep track at all. There aren't more than two halves, so how do you know?
When I owned and ran my fleet service business we worked on more than 50% Ford gas engines. The rest was a mix of diesels and other manufacture's stuff. On request I would produce a yearly reports of costs for my customers. The gas engines vehicles were more economical as a whole when you looked at the fleet and not just one data point vs another. And it wasn't by a little bit. However, my reports didn't include fuel costs.
When I owned and ran my fleet service business we worked on more than 50% Ford gas engines. The rest was a mix of diesels and other manufacture's stuff. On request I would produce a yearly reports of costs for my customers. The gas engines vehicles were more economical as a whole when you looked at the fleet and not just one data point vs another. And it wasn't by a little bit. However, my reports didn't include fuel costs.











