Lower, Mark A (1860) Patronymica Britannica: a dictionary of the family names of the United Kingdom. London: J.R. Smith. Public Domain.
CAR
As described in historical dictionaries
Patronymica Britannica (1860)
j"CAER. CAR. The initial syllable of many local names, which have become surnames, especiallj' in Scotland and Cornwall. Jt is a Celtic word signifying " an artificial military strength, whether fort or castle."