FWIW, I hadn't heard it either. This dealer website http://www.mikeabbasclassiccars.co.uk/Carhistory.htm claims to have handled the car at some point.Timeless A-Peel wrote: It was just a part of the Avengers entry that I hadn't heard before, and thought I'd see if anyone had heard the same. It sounded unlikely to me, but one never knows.
A comprehensive article on Avengers' vehicles by "Tony O'Grady"* was published in issue #8 of Time Screen in December 1986. It doesn't mention what happened to the car but does say that Diana Rigg's personal transport was a standard Mini. It also, incidentally, claims that "powder blue" was the official Lotus colour code designation.
~iw
(*Tony O'Grady was a pseudonym used by Brian Clemens in the 50's and 60's).