Hi Steviewevie. No, I don't think it's electrochromic. According to wikipedia they only introduced electrochromic mirrors in 2006 models on (mine's a 2003). I think it's a standard electric, heated mirror. I've photos attached, can you tell by looking at it?
Incidentally, as you can see from the photos it's only one part that's snapped. It seems I have to get a whole new mirror, not just the part that has snapped - is that right?