Wasn't/Isn't the 6R4 the quickest production (homologation production) 0-60 accelerating car ever? Recorded a 2.45 0-60 in road trim?

It has the same 3.5litre V6 as the Jag XJ220 without the turbo's.... I thought the 6R4's were turbocharged? If not how could they make such ridiculous power and amazing performance stats?