Don't worry. I was a half an hour late to my own ceremony because the limo driver picked me up late and then went the wrong way. Maybe the bride will be late today, too, and you won't miss much. Even if you are really late, the bride and groom sit with their backs to the door, they'll never know!
My car caught fire in the way to one of my cousins wedding. I got to the reception only & people were sniffing around asking what was burning. Um, my clothes held the smoke, thanks.