Floyd Clymer the US publisher, long since dead, republished the first series, unsure when, but late 1960s/early 1970s is a good bet.
Then in Sydney Ron Ferguson of “Vintage & Veteran Motor books”, republished both editions, likely in 1980s.
Ron Ferguson died under mysterious circumstances and I am unsure if his publishing company still exists.
So how do you get one and what might they be worth today?
Ebay is a good bet as are some UK second hand booksellers, such as Pook books, MBPA etc. Here in Oz sometimes books show up at swap meets and a telephone call to Anand at Autobookworld in Sydney 02.9299.6669 could prove helpful.
Price wise ?...UK£15+, A$25 etc each.
Obviously the original series would be more sort after and perhaps cost more, but the information, drawings etc is the same in all the various editions.