I don't do 30 in 6th, I'm not saying you can't but why would you want too? 4th I'm normally in or 5th if it's a constant 30 on a long road.
But being in 6th rather than 4th or 5th requires more throttle therefore using more fuel ?
I don't see any advantages being in 6th at 30 in a CTR. The car isn't economical in any shape or form. Just stick it in 4th and enjoy it.
There is yes. But there is also advantages to eating salad.For maintaining 30mph? All you need is to press the peddle just enough to open the butterfly valve, so no more throttle in 6th than in 4th or 5th.
It's up to you how you drive your own car, but there ARE advantages to fuel economy by being in 6th.