The BMW E12 launched the popular BMW 5 series in 1972 in an attempt to go headlight-to-headlight with luxury car leader Mercedes-Benz, eventually setting the standard for fine handling, driver safety and luxurious appointments. The ever-evolving line of executive class, mid-size cars -- now in its sixth generation -- is responsible for approximately 50 percent of total BMW profits.

Originally designed by Marcello Gandini, famed designer of the Alfa Romeo Alfetta and the Fiat 132, the sleek lines of the first generation were based on Geneva's Bertone BMW Garmisch 2002ti show car from 1970. This initial line was revamped several times and then discontinued in 1981.

Each generation of the BMW5 series brought something new to the table. The second generation E28 M5, sold only in Europe, was the fastest production sedan in the world at its launch in 1984. The third generation BMW 5 series featured a longer chassis, stiffer body and ABS airbags as well as a sleeker and more aerodynamic design. This generation won several awards for its reliability and safety and was one of BMW's most popular lines.

BMW's attention to quality was enlarged upon by the fourth generation BMW 5 series E39 530i, which earned the highest Consumer Reports rating in history. This generation also featured a new bumper, changes to the internal electronics and an updated bumper. The fifth generation of the series carried on the tradition of excellence with striking innovations in technology – including an eight-speed transmission -- though the late Davide Arcangeli's design was not popular, particularly for the extra layer of metal on the trunk. This was referred to by critics as the "Bangle butt" in honor of BMW's controversial design chief, Chris Bangle.

The sixth generation BMW 5 series line is offered in both a sedan and a touring style and is the only luxury car on the market that is available in a manual transmission. The 2012 BMW ActiveHybrid engine combines an electric motor and a turbo six-in-line engine with an eight-speed automatic transmission for those consumers who want luxury and power along with environmental responsibility.