Sorry it’s so long…

It seems like a semi-truck and trailer (or just any vehicle) would use more a lot more gas carrying a full heavy load than carrying no load, right? It makes perfect sense. But this is puzzling me:

If the truck has a more load, it has more mass and then more momentum. So it takes more gas to get trucking moving to like 50 m/h but it would keep rolling for much longer because of momentum. (and with no load, it takes less gas to get to 50 m/h, but it roles for shorter, and so it would take roughly the same amount of gas I assume.)

I know it would still take a bit more gas but only because of extra friction and having to stop and turn on corners, but I want to eliminate those factors and say the truck is moving on a very very long straight highway (to take full advantage of using it’s momentum).
(Now the air resistance won’t matter because the truck has the same shape and size and the friction won’t matter much because it’s only a little bit (plus there’s less friction the faster you go)

So… would a truck carrying a *very heavy load* use the same amount of gas traveling on that highway (elimination those factors) as *carrying no load*?

Sorry for using so much punctuation too lol.