Last year we edited out everybodies number plates before putting Galleries onto the website, which added a lot of extra time and hassle. This year we havent bothered and have had no complaints..so far.
The way I see it is, if your on track you know fine well your picture will be taken, bring some duct tape and stick it over the plate is the easy solution, I know I would if i was taking a car on track that still had the manufacturers warranty.