[steely]

Yes, the 'run-up' sort of took me by surprise too.
I'll go with the sweet-spot theory. (aka demographics, income, zip code, annual mileage, plus magic)
I'll just add too that some companies give you a discounted rate on the daily driver type of insurance if you have your homeowners with them as well. I'm not saying it's news, but it did play a key role is my decision when I was rate shopping for my dd's last year. (rule didn't apply to my p-car)