<P> E89 Z4 - front </P> <P> Sometimes the model series are referred to by their German pronunciation: "Einser" ("One - er") for the 1 Series, "Dreier" ("Three - er") for the 3 Series, "Fünfer" ("Five - er") for the 5 Series, "Sechser" ("Six - er") for the 6 Series and "Siebener" ("Seven - er") for the 7 Series . These are not actually slang, but are the normal way that such letters and numbers are pronounced in German . </P> <P> The BMW i is a sub-brand of BMW founded in 2011 to design and manufacture plug - in electric vehicles . The sub-brand initial plans called for the release of two vehicles; series production of the BMW i3 all - electric car began in September 2013, and the market launch took place in November 2013 with the first retail deliveries in Germany . The BMW i8 sports plug - in hybrid car was launched in Germany in June 2014 . </P> <P> In 2014, BMW developed a prototype of street lights equipped with power sockets to charge electric cars, called Light and Charge . Two of these charging facilities were installed at BMW's headquarters in Munich . In 2015, BMW in cooperation with SCHERM Group has started deploying electric trucks on European roads, making it the first company to ever do so . The truck itself is manufactured by the Terberg Group, one of the world's largest independent specialist vehicle suppliers . </P>

What does the i on bmw stand for