Years ago, when I owned my first Avanti, (Studebaker Avanti R3623), I used to drive it from Boston to Augusta, Maine frequently to visit friends....As that Avanti had an R2 engine, I would remove the blower belts before leaving, ( approx 500 mile round trip), to save wear and tear on the Paxton supercharger.
That Avanti seemed to cruise very well at 60-70 mph, although no doubt the R2 carb pushed through more fuel than was necessary!!
Back in the day, did any of you Avanti owners 'pop' the blower belts before heading out on an extended trip??