Not entirely true. A few years ago, Jaguar discovered some E-Type VIN's that hadn't been issued to cars. So they built some brand new, original spec, E-Types. Granted, there were only half a dozen, and they sold out instantly for large sums of money, but it has happened.
There are also "better than new" rebuilds out there for Jaguar, MG and others-- a company will buy an old MGB, for instance, tear it down to the frame, and build it back up with new or refurbished parts, along with fixing any incidental issues from manufacture (or 40+ years of abuse), tune up the engine, suspension, beef up the brakes, blueprint the rebuilt engine-- the result is a car that looks and sounds like the original, but drives and handles substantially better.
A bit like what Arax was doing with Kiev cameras.
Back in the late 1980's, when I still had my MGB, Moss Motors (who bought up the North American spare parts of British Leyland), was so heavily involved in fabrication that they built a "brand new" MGB roadster from parts at a North American car show-- they started unloading parts from a truck on Thursday, and Sunday they fired up the new car and drove it around.
Yes, I realize these are anomalies.