A little explanation of the motorcycle ride debunking here: http://www.neilgaiman.com/journal/2004_05_16_archive.asp
I'm more skeptical of the debunking than the motorcycle ride. She has to walk a fine line legally. It sounds quite possible that after taking the car tour and getting the low down on area rad levels that she was able to slip through barracades tour a bit on a two-wheeler. Then she could shrug her shoulders about it when the authorities got nasty. "Oh I really just..."