Below I try to summarize the typical trends I see on the streets about what are the typical cars here, and who drives them usually. Please keep in mind, that is not official, and based on my own observation!
Ford Mustang: You'd say its convertible version must be the typical car on the street. Well you're wrong. According to my friends who recently came back from Hawaii, that's true in Hawaii only. However Mustang is the 2nd most common car though. The current and the previous generation. Some from the 60's did survived, but classic cars are rare to see here, and are usually driven by Mexicans (see below).
Usual driver is a blond girl/lady. It's cheap to lease (below $300), but its functions are limited (no space in the back etc.) so it is a typicall 2nd car in the family.
Toyota Prius: Now this is the No. 1 car on the streets. Here in Northern Cali everyone is 'environment-aware'. Which is a bit different from what we Europeans would think about being environment friendly, thinking about that trash produced by a single lunch of a single person in a fast-food restaurant fills a family sized trash bin. So they think driving a Prius not only saves them money on gas but also helps the environment (even though it is not the case at all:
link). Well the battery dies in 3 years (LiOn!) and is full with hazardous materials. But still, it's a smug thing I guess.
Usual driver are family mums, maybe older hippies. Usual 2nd car in the family with almost no trunk space (well at least in US measures).
Pick-up truck (Dodge Ram, Chevrolet Heavy Duty Truck, Ford F-x50): Mexican drivers. Landscaping and similar jobs. These cars don't exist in Europe. They're huge. They have enough power to act as a camion. And sometimes they
_are_ used as one. Some choose Toyota pick-up trucks. Probably they drink less gas and cheaper to buy (I doubt, but didn't double check).
Older pick-up trucks (and any classic (muscle)cars): Mexican drivers. Exclusively. And me, when I pay back my mortgage on the apartment in Budapest (the target is a 1971-74 Dodge Charger).
Chrysler 300 C: If it's not used as a limo, it is pimped (customized). No exceptions. Drivers are exclusively (and again not limos! those are driven by Indian people only!) coming from the Afro-American race. Wannabe rappers. This car is relatively an older model, so it is cheap. Well Chrysler and Dodge are cheap in general.
Dodge Charger: Well it is a 300 C in a different form, but there's no doubt it. Apart from mine and a few fellow Charger drivers, all the Chargers must be customized, and their drivers are coming from the same segment as Chrysler 300 C. I couldn't figure out yet, what makes the difference. I mean why certain people choose the 300 C and others the Charger. Someday this secret shall be revealed! The Charger however is never used as a limo. Haven't seen one. But it is a good family car. It's huge (BMW 7xx size) and the trunk is big, too. Many people chose it as a first family car (I'm also in that market segment).
In Cali there're a few other kind of Fords, too. Usually SUVs or mini-vans (mini, LOL). Some Lincolns, too (== luxury Ford), but they're not significant.
There're other rules, too: old Buicks are usually driven by Afro-Americans, too. If it is a Toyota (and not a Prius), the driver is Indian. The older the car the higher the possibility. Hyundais are exclusively driven by Indian people. With Kia it is about 80% chance. Honda (Civic) usually has an Asian driver (there's about a 10% exception). Behind the steering wheels of BMWs are usually older dudes. In their mid-life crisis. Must be a convertible. Minis are getting popular here, too (what a disappointment), but exclusively the sport version.
Altogether 'domestic' cars are not too popular in Cali. Toyota rules the market with Hyundai and Honda. Americans here are tend to buy the ugliest and the most unattractive looking cars ever. It's almost like making it up for the cars they had between te 50's and 70's. Even young-timer American cars fall into that category. (The term young-timer is a strange term here. Most Americans keep their cars until the wheels fall off, so it is not rare to see 15-20 years old cars on the streets). Check out the models they had from the 90s till recently. But it is changing, thanks God! Well I'm not sure I will ever like the new Buicks or Lincolns but the new Dodges are cool. And muscle cars are coming back, too. The Ford Mustang, Dodge Challenger and Chevrolet Camaro are really popular, and relatively cheap to buy or lease. And that's a good thing!! Those cars represent what an American car should always be. At least for us, Europeans.