Dude, learn the bus schedules. SD has a decent bus system.<br />
I'd not recommend a car for several reasons - 1st insurance will kill you out there! 2nd SD has a car theft problem, and if your car can be easily stolen or is a desirable one, it will be gone eventually. 3rd, maintenance and repairs will cost a lot for your old beater, and may not be worth it if your car is worth $1000 or $2000. 4th smog checks will be a major pain, and if your car doesn't pass smog, you have to repair it which will cost $$$.<br />
Go ahead and get a good mountain bike (get a lock too!), but I encourage you not to rely on it as your sole transportation this winter. The rainy season is starting soon, and there will be rainy and wet days.<br />
If you plan to live - live there forever or for years and years, then look to purchase a car, but do your homework on theft rates, insurance, going rates for repair, smog check rules, and then decide if it is for you.
A motor scooter is just fine, for the city area and open areas of AlPine, Ramona, or Borago Springs. I think the bikers will laugh at you unless its a Harley Davidson.
nice, all depends on what location you're in and your lifestyle. i haven't been there in 18 months.
car=useable in all weather and ya can take home stuff too.
You are going to need a car here :)