The Ford Mustang is celebrating its 50th anniversary this year, and that's a grand thing. As the announcer in this old ad tells you all about the competition, you can hear just how many marques its outlasted. And it might be because of the awful Mustang II.

The Mustang's history is built first upon the fact that it defined the "pony car" niche, and then that it dominated the muscle car niche, along with the Chevy Camaro. Pony cars like the Barracuda, Javelin, and Firebird just plain don't exist anymore, and you won't find muscle cars like the Oldsmobile 442, the Buick Gran Sport, or the Plymouth Road Runner, either.

Part of the reason why the Mustang has lasted so long is because it's never strayed too far from its roots, and part of the reason is because it's always adapted to a changing market.

But with the Mustang II, that changing market forced it to stray from its roots, and it still looms over Mustang fans to this day.

Just from watching the ad, you can tell something has gone horribly wrong on Planet Mustang. There are no storied nameplates like the Cobra Jet or the GT500, no mentions of "muscle," or "power."

Instead, it was a "small personal car," whatever that means.

Selling points didn't include how fast it was, but rather how much gas you'd save with its four-cylinder engine, a result of the first Oil Crisis.

But when it first went on sale, that four-pot put out only 88 horses. And the optional V6 put out just over 100, as if that made things any better.

The successor to Steve McQueen's stallion was choked off, throttled not by a lead foot, but by the gas pump.

And while we can lament all day about the Ford Mustang II, the fact of the matter is, it sold in huge numbers. It's possibly why the Mustang is still here.