that sounds much cooler...lol

I think it'* more like 'diagnostic sweep'.

i dont remember 100% but i think my 86 Park Ave'* gas gage didnt move when u shut it off, but the gas gage was the only gage next to the speedo AND I HATED THAT!]
My Bonneville'* gages sweep and yes it looks neat lol, my tach sits were ever it is when i shut it off, but if i close the door hard enough it falls to 0 meh no biggie to me, ive shutt he car off befor and none of the gages have moved, gas stays at lets say half tank, boost at -70, temp at mid range, and oil at compleat MAX....it doesnt work all the time....hehe i could care less, as long as they sweep

In general it'* called "proveout," but the term is usually applied to the circuit that illuminates all the warning lights during startup.

Getting the step motors that drive those gauges to do a mechanical wave at you is more in the area of Showing Off than for any official purpose, although I guess maybe it serves to re-zero the gauges at power-up. They could achieve the same thing by just pulling them all straight to zero to catch any that might have wandered elsewhere on the scale while the power was off, but exercising them all the way up, then all the way down probably doesn't hurt either.

Anyway, it looks cool, so there.