Value wise having one car may depreciate faster than having 2 but in terms of actual money being spent it's still going to be cheaper/better value to have one car.
If you buy a new car that's a mix of both dd and weekend it's most likely going to be cheaper than if you bought 2 new cars with specific purposes (both new for sake of argument)
If you go the used route you're still in a similar situation. You can buy a better/less mileage car that's a mix of what you need versus splitting your budget and getting 2 but most likely higher mileage and potentially more issues cars that you can split your driving.
I tell you what. You drive your "special" car on daily basis and tell me how special it is 3-5 years down the road. If you have a daily and a special car for those special days, chances are you will have that car for a VERY VERY long time. You will also care for it lot more as it will not be exposed to daily tear and wear. I've been down this road and I've seen plenty of folks do it as well.
Cost wise, ok fine, let's say you are right. But you will NOT have that car for a VERY long time, neither will you care for it much 3-5 years into the ownership.
I won't even get into the TIME it takes to keep the daily clean (like that special car should be). I remember I used to wash my car every 3-4 days to keep it in tip top shape....which it was never in anyways.
Then there is the whole risk thing. When you drive daily you WILL have dings/paint scratches and your chances of accident rises significantly.
Find out for yourself. It's not for everyone, but I found that it's best to keep the 2 completely separate. I think it's just better that way ALL around.
PS. Climate might have a lot to do with it. I'm in northeast and noticed you are in Cali (better climate situation)