This document explains every study done between WW2 and about 2000.
http://deepblue.lib.umich.edu/bitstr...pdf?sequence=2
Upshot of ~100 pages is
if you need accurate details (how fast am I going) = numeric display is best (accurate to smallest detail)
if you need to check something (am I going too fast or too slow) = pointer display is best (shows surrounding ranges for comparison)
In both cases of course you'd need to have some mental idea of what you SHOULD be doing ... or colour sections on the display can indicate for you. But pointer position indicators in every test led to much faster acquisition of the data than numeric, which has to be "read" not just recognised at a glance.