I have spent a lot of time researching car rentals in the last few years.
- The best rates are often 6-8 weeks before your trip. Thankfully, most car rental places offer reservations without even a credit card guarantee - so I just book at something acceptable and continue watching closer to the trip.
- Car rental prices are even more opaque than flight prices. It changes constantly and it can be endlessly frustrating. One trip, Company A is cheaper, next trip Company B is cheaper, and so on. It also can change by day or by hour. I find it takes a lot of work and effort to get the best prices. I used to be super anal...nowadays I get fed up more easily and settle for good enough.
- offsite vs onsite...you have to price it out individually (for every possible company). Onsite has higher property fees...but that is often offset by lower rental fees.
- Coupon codes can be really helpful. That said, because you have worries about insurance, you might be best booking through a European company which often includes insurance.
- Some companies charge drop off fees, some companies don't. Good to be aware of this.
Here was my experience back in 2015. I started with Hertz but ended up switching for various reasons.
I started looking seriously in March for a July trip (typically I find best prices for car rentals about 2 months out although occasionally I try much farther out and rebook if prices drop). Sometimes airport locations are cheaper, sometimes offsite is cheaper. All the places I looked in Cali, offsite was cheaper, even including cost of uber to pick up.
Reservation #1:
Booked: March 2015 for July 2015 trip
Hertz 1 week intermediate vehicle. pick up San Jose (offsite), drop off Anaheim. $314 incl all taxes and fees (watch for that - the car was only $282), AAA discount.
Reservation #2:
Booked: June 17 2015 for July 10 2015 pickup
Hertz 1 week intermediate vehicle, pick up Burbank (offsite), dropoff Anaheim. $249.85 incl all taxes and fees. AAA discount + $20 coupon from Hertz website
Reservation #3:
Booked: June 17 2015 for July 10 pickup
Avis 1 week convertible, pick up Burbank (offsite), dropoff Anaheim. $356.09 incl all taxes and fees. Maybe AAA discount? I forget. I also used a $30 off coupon from somewhere.
We went with the convertible :) It was a blast - but I had to pack VERY little. We spent almost 2 weeks with just 2 carry-ons and a backpack for a family of 4 (2 teens). I did laundry twice and packed super light. Worth it though - the convertible was super fun in California!