Erm, yeah, you're supposed to leave a car sized gap. I only recently passed my test and I was TAUGHT by my instructor to leave a car sized gap. It's a safe stopping distance away and if a car hits you from behind it means that you're less likely to be shunted into the car in front.
Things that annoy me:
People getting too close when I'm at traffic lights. 
People standing too close behind me when I'm in a queue. This happened to me yesterday when I was in H&M. A woman was literally breathing down my neck so I stepped forward a bit to stop her from invading my personal space. She also stepped forward! Fuck off fuck off fuck off!
Grumpy bus drivers.
Lovely, friendly bus drivers who stop and chat to everyone, therefore delaying the journey and making you late for work
. You're lovely and all BUT GET A MOVE ON.
Thank god I don't have to get the bus much anymore!
People who don't tell their children off when they're being naughty, they just let them carry on. People who let their children run wild and then look at you as if to say "aren't they so cute." No, they're not cute - they're being a pain in the arse.
People in general. People are arseholes.
I have low tolerance for people. 