Depends what kind you use, an octane booster should have the same effect as using premium fuel as you're just increasing the octane number. I know some people who use an additive every tankful of diesel just to keep the injectors from clogging up, but octane boosters are different.
In truth, ethanol is an additive to 84 octane 100% gasoline(E0), making 87 octane, E10. Since, E0, in my last five low compression ratio, 87 octane engined cars, gave 8% ,8%, 7%-8%, 7% & 6% better MPG, ethanol isn't functioning properly. Also, some vehicles, burning E0, gave excellent emissions tests.
I use Techron on my truck and it works great. I get 2-3 more MPG's.
years ago I used a fuel additive product from amsoil that made a big improvement and it smoothed out my engine and I didn,t have 50,000 on my chev impala.. the cost was up there to where I didn,t think it was cost effective tho !!!!