I never trust the 'spends lunch break in car' types. First one I ran into was listening to Rush Deadbaugh and the second was talking to god or something.

I don't mind grabbing a beer with coworkers after work, but that's it. In work I'd rather have my mind somewhere else.

"Doesn't talk unless spoken to " is fine if you don't want to talk about you private life but if it is work related you need to speak up when it's necessary. Otherwise some co-workers start taking credit for shit you've done. Not to mention if you don't build some rapport with co-workers good chance they don't recommend you for a promotion or a raise or something even if you do your job well. Not because they hate you or something just that they forgot what you do at work and it's your job to remind people of the work you've done and that only happens when you talk.

Also in large companies it's good to be in the loop of what's going on in the office, it's how you can sniff out an opportunity for a raise or promotion or know when to leave before the ship sinks. So socialize at least a bit at work, you can do that without talking much about your private life.