Although I am a newbie really, I do know a bit about aircraft.
The La7 would have the worst known fuel economy in the game for propellor driven fighters. This, along with the fact that it has limited ammo, are the only reasons (a lot of players believe) that the La7 does not have a cost of perks to use it (for example, the same as the F4U-C...the one with 20mm cannons?)
I have been told by La7 experts in the game, that when in one and 1 sector from home, leave no less than 1/2 left in your main tank...otherwise you will run out. This is even with fuel conservation techniques.