Just found this on the Cummins website. Interesting, interesting even though it is targeted more at truck drivers.
Cummins MPG Guide - Secrets to Better Fuel Economy
Below is their summary. I was surprised at the impact of new tires vs. broken in tires.
Rock-Solid Rules
§ Every 2% reduction in aerodynamic drag results in approximately 1% improvement
in fuel economy.
§ Above 55 mph, each 1 mph increase in vehicle speed decreases fuel economy by
0.1 mpg.
§ Worn tires provide better fuel economy than new tires, up to 7% better fuel economy.
§ Used lug drive tires can get up to 0.4 mpg better than new lug tires.
§ Ribbed tires on the drive axles provide 2–4% better fuel economy than lugged tires.
§ Every 10 psi that a tire is underinflated reduces fuel economy by 1%.
§ The break-in period for tires is between 35,000 and 50,000 miles.
§ Tires make biggest difference in mpg below around 50 mph; aerodynamics is the
most important factor over around 50 mph.
§ The most efficient drivers get about 30% better fuel economy than the least efficient
drivers.
§ Idle time is costly. Every hour of idle time in a long-haul operation can decrease fuel
efficiency by 1%.