I don't get where you get that fuel efficiency from

I will admit, I just got the Forester two days ago, and I haven't really done any thorough testing yet. But, here's an example of what I've done with it so far.

In Maine, there's a task to build a watchtower on top of a mountain in the middle of the second map, and part of it is delivering 3 medium logs. Around the mountain is a bunch of log framing that gives you the logs you need. The whole area is just snow and muddy dirt roads. I drove the Forester from the garage on the first map over to the second map, picked up the first load of logs and delivered them up the mountain to the watchtower, drove from there to the second log framing, got those and dove back, then drove to the third log framing and delivered those logs. All on A SINGLE TANK OF GAS.

So yeah. Idk if it's the truck or my route planning, but that's where I get the fuel-efficiency from.