Best Place to Service the Prius in Costa Mesa, CA area.

I am Arul from Costa Mesa and have a 2007 blue Prius. I have driven the car from Portland OR to Princeton NJ and from Princeton NJ to Costa Mesa CA. So the car has travelled through the length and breadth of the country.I really love the car and my only concern is that I am unable to give it an optimal service from the authorized service centers that I have been using.
I have driven the Prius for 32000 miles now. I wanted to take it for the 30K service.
I moved to SoCal about 8 months ago and since my move, I haven't been able to find a good authorized service station for Prius.
I tried at Tustin Toyota and Power Toyota Irvine, both of which appear to have merits and awards according to Toyota's website. I got a satisfactory service from Tustin Toyota but Power Toyota Irvine sucked in both service and customer treatment.
When I constraint my travel on non highway/freeway roads and restrict my speed to 40mph or lower, I can achieve between 47 - 52 mpg. If I enter the freeway and travel at about 65mph or lower, then I can achieve a mileage of 45mpg. However, if I reach to 80 - 90mph then I only get 33 - 36mpg.
I hear from many users in chat rooms that they get between 47-52 mpg easily. I follow the guidelines as mentioned in chicagoprius website and still hardly manage to get 50 mpg once in a while.
I guess the service that my Prius gets here is not optimal. I request you all to kindly provide me with options to get the best service my car.
Thank you for your time and input
Best wishes
Arul