Try fox rental cars (don't know if they are available up north, but I get them for $10/day)
As to Highway 1, I did that trip in 07 and spent 5 days between Carmel and San Simeon. There are some AWESOME things to see. Eat at Nepenthe, Partington's Cove, Hearst Castle, Elephant Seal Beach (just north of the castle), all 400+ turn outs, etc...
If you and your loved one wants to do the Zoo, let me know. If I accompany you, I can get 2 people in for free as my guests
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