Remember the 3.5 was a stroker motor. Rev limit was 6200 rpm, so 4000
at 80 gives around 125 mph for the top end, which was the design spec
(same for the 4.5L with 3.23 gears and a 5600 rpm limit, or some thing
like that). A real screamer.
No tachometer on the 72 US model, so I don't know
Huuh? You mean 80mph? That's about 128kmh, I think most cars (apart from
the latest ones with 500 gears in the box) would do round about 4k at
128kmh.
Speaking like a general, cars are designed to be efficient round about
90-100kmh, given that is the usual cruising speed in most parts of the
wo
