[wilf leek]

Mechanical usually more accurate than electrical, plus you get the 270 degree needle sweep.

However - not 100% accurate - no auto guages are except high end race items, and far more difficult to plumb - the capillary line is relatively fragile and needs care in it's routing.

To get some idea of the gauge's (any temp guage) accuracy - put the sender (elec, or the bulb on the end of a mechanical unit capillary line) into a pan of boiling water - that is always at 100C. (or close enough to not matter).

I guess it's your choice.