By the time we got there, the warning light on the dash disappeared-"Smart Key no longer in vehicle"- so I knew we were safe to shut it off so I could gas it up. The car started fine after that, and the remainder of the trip went off without a hitch. We're now on our way home, and at the same hotel. So kids- find out what battery you need, and learn to take apart your fob to replace it. Without that knowledge, I would have been stranded 6 hours from home with a heavy, British paperweight.