[elhigh]

Another Minnesotan! We're eaten up with them around here. I've been living in Tennessee for 30 years now and I still describe myself as a Minnesotan. I'll give it up when I die, not one moment sooner.

Start a garage page for your trucks.

The operating envelope you describe isn't the best for aero improvements. Your best returns will probably be realized from aggressive weight reduction, engine tuning and serious nut adjustment. Anywhere you spend some time at highway speeds the aero improvements will be in your favor and should pay off eventually, but all your stop-and-go is keeping your numbers down.

Everything that turns, especially that changes speed when your vehicle changes speed, is eating horsepower with every speed change, and sometimes wastefully dumping it when you slow down again. Engine-powered fans aren't as efficient as electric fans that run at a constant speed and only turn on when needed. Lighter wheels and tires are easier to speed up from a stop and slow down again - you could coast longer and brake later - maybe a bad habit in a state with six months of winter. Lighter drivetrain components are admittedly a pretty spendy thing to concentrate on, but if there is, for instance, a lightweight race-oriented driveshaft you could install in place of your heavy existing one, that would be a good thing.

In your situation, think "race." Weight is the enemy because you spend a lot of time changing speed and direction and inertia means all that mass doesn't want to try something new. Weight that isn't there doesn't need convincing = good. Read up on how racers prep their vehicles so they're only equipped with the necessities.

You might get a big boost from incorporating an engine kill switch so you can easily turn your engine off as you approach stops or otherwise need to kill speed, while keeping your accessories powered.

In the city on hot days I turn off my AC at stops and during acceleration, it only gets turned on for the coastdown approaching stops and turns. I'm warmer than I might be, but it's still cooler than walking or riding around in an unventilated greenhouse.

There was at least one other thread here that delved deeply into the delivery mission and how you might best optimize for fuel mileage, you could do a quick text search for that.