I think the answer is
Supersaturation
My prefix - ( i ) are this/these.
This is the symbol for The Incredibles who are SUPERSSUPER(S)
My infix - The sixth lost its sixth.
The sixth planet from the Sun is SATURN, without its sixth letter is SATUR
My suffix - Even though short, eating the first still leaves enough.
I think this is RATION because eating the first ration still leaves enough food, even though it is in short supply.
OP clarification: SATUR ends in R, RATION starts with R, eating the R is fine because R is already present in SATUR, so it involves the overlap.
My whole - A nice sight to see on a winter day's drive.
I think the idea here is that supersaturation equates to more snow on the ground since it cannot be absorbed into it.
OP clarification: Supersaturation of the salt leaves salt crystals visible on the road, meaning the salt is left over and the roads should be dry.