LOL folks. My '06 A4 is a light gray; evidently a common color of the time. I can re-call one or two or maybe another occasion that I stood by the drivers door trying to un-lock it only to realize mine was a few vehicles over. Ouch!
Back in the 70s, this happened to me - driving a gray Honda Accord, you know, when they only came in Gray, Blue and Red for that year. I was coming out of a mall, hands sorta full, unlocked the car, got in, started it up, turned to back out, ready to move, looked around and started thinking about the mess 'my wife must've left about', then saw the Garfield stuck to the rear window - and froze.
I studied the car while sitting there idling, and realized to my dismay that this was NOT my car at all. I calmly shut it off and got out, locked it up and found my car just 2 places away and up a row. I took the car to the dealer the next day, and asked whassup? They told me 'hey, we made 50000 accords that year, in 3 colors, the only difference between them was transmission, 5-sp or Auto. Our keys that year had 10000 different combinations, so go figure - about 1 in 3 or so will match.'
I didn't even try to have the locks changed, just grinned and walked off - things are a bit different today ...