My opinion...the market for magazines that focus on "Classics & Exotics" in USA is very small; most readers fall into the entrly level sports, Minivan review or hot/rod tuner area.
The one exception is Sports Car Market ....which is the Bible on Collectors Cars; the editor has no fear of "valuing" cars at market, and has been in many duels with dealers, lawyers, auctions, sellers who have challenged him....his 30 yr reputation is stellar.
http://www.magazines.com/product/sports-car-marketI would also recommend OCTANE.....its very close to style of MT Classic.
The Brits have two mags that are hit & miss: CLassic & Sports Car; Thoroughbred & Classic Cars
.....they seem to focus on Saloons a lot....and seem to feature Jag MkII every month; and half magazine is 2 inch classified adverts
The Editors actually asked me for a crtique this holiday, as I sent in a Letter-to-Editor essay on buying my SL; and they wanted a a USA readers opinion. I told them to follow Octane.
This is a good US magazine
http://www.magazines.com/product/hemmings-sports-exotic-carThe main USA markets....each magazine has shrunk 50% in ad pages in last 5yrs:
-Motor Trend / Car Driver: these are the Big three focus, and mini vans, econobox reviews
-Road Track / Automobile: enthusiast focus, rarely focus on classics; often include SUVs, crossovers
-Hot Rod, Mopar, Muscle Cars, Mustang, etc: these are niche focused on one make usually and articles are usually half page.
-European Car, Tuner: these used to be classics, but are mostly asian, tuner focused
-Cars/Girls: Rides, Exotics, Low Riders