if you have seen Martin Jagersand's, graph of power vs. speed for his
Vanagon Westy you might look at claims of "feelings of reserve power at 80
mph" with some scepticism.

He calculated a drag loss expressed as power (kW, and power is a cube
function, in theory, of velocity, air resistance is a square function of
velocity) of approx.:

19 kW at 23.5 m/s (25.5 hp at 53 mph)
31 kW at 25.5 m/s  (42 hp at 57 mph)
36 kW at 27 m/s (48 hp at 60 mph)

See how the power required goes up?

The numbers are a bit iffy (eyeballing from his graph), but the trend is
evident.

Alistair
--
'82 Westy -> diesel converted to gas in '94
albell@uvic.ca
http://members.shaw.ca/albell