Video does have problems with white ( avoid white ) in the sun. The cinegama curve should help you keep the highlights from burning out. Cloudy days or at least clouds in the sky help reduce sharp contrast from sun to shadow. Do you have clouds in Ca? We are a little short of them here in AZ
Well If you got the the money and the time you could place the car on a trailer and have it towed while you filmed. You could get some c-stands and securely strap them down and use a large scrim maybe placed above the car to help cut down the harshness of the sun. I have seen this technique used on big budget movies using special camera trucks and attachments.
