I live in Japan but been to SoCal a few times, For automotive photography I'd recommend PCH, Malibu Canyons, and here:
I don't know where this is, but the backdrop of Downtown LA at sunset could win you prizes in automotive photography...
I also did a photoshoot of Penske Mustang GT I was renting at San Diego Harbor. Epic location! (I pretty much sucked at photography 3 years ago, when I shot this, but at least it will give you an idea of the location)
I am officially jealous of car photographers in Cali. Tokyo is really challenging in this regard, and as soon as you find something there is gonna be a goon security guard trying to kick you out...
Basically to make a good backdrop your best friends are open roads, old buildings, wide spaces, mountains, and sunset/sunrise
your enemies are trees, grass, power lines, other cars and any time between 10am and late afternoon. Have fun. post some shots if you get a chance