First generation (1964–1973)
The original. A cult classic pony-car, immortalized through appearances in films, games, and everything in between. It revolutionized the cheap sports-car market in the US, and was an essential part of the American Dream in the 60's, and still fetches a hefty premium on classic car auctions.
Second generation (1974–1978)
The disappointment. After the massive success of the first generation, the second generation was such a commercial failure that hardly anyone knows what it looks like. The 70's oil crisis hit American manufacturers hard, and they all struggled with the concept of small sports cars. A large blemish on back pages of a fantastic marque.
Third generation (1979–1993)
While it wasn't exactly a legendary machine, the third gen Mustang worked its way back into the good books of car enthusiasts with a few interesting engine options in the lineup. Good looks for the Fox body Mustang and its 5.0 liter V8 made it a popular choice for drag racers.
Fourth generation (1994–2004)
The fourth generation Mustang had demure looks and the sleek body style made it a popular choice for parents looking for high-school graduation gifts. It had decent performance, and in Cobra R form, it was blisteringly fast, a proper return for the Mustang badge.
Fifth generation (2005–2014)
Probably the most successful Mustang model since the original. The modern Mustang aped the '64 Mustang, as a wave of retro-styled muscle cars hit the market. Long running competitors in the form of the Dodge Challenger, Charger, and the Chevrolet Camaro made comebacks at around the same time as the fifth gen Mustang, with many calling it the “second coming” of the muscle car heydays.
Sixth generation (2015-)
There's a new Mustang coming out, and its all new. Modernizing the Mustang involves major changes to the archaic suspension setups and smaller but more powerful engines. Ford's engineering expertise is being fueled into the development of the latest, and possibly greatest Mustang, and seeing what Ford has been working on in recent years, it all looks very promising. Plus, just look at it. People will throng to the dealerships just for the looks.