There's a bit of advertiser's licence in the advert in OG's link. Water boils at 100deg - more like 120deg when it's pressurised, as car systems are. Water + antifreeze goes down to -20 deg before freezing - my Volvo handbook says -35deg. On top of that I've never had any antifreeze added, or a change, in 10 years/180,000 miles on the current car (or the previous Volvo). To change to waterless, using the advert figures, would cost in the region of £200. I can't see the advantage.