After numerous delays, the 2012 Fisker Karma plug-in electric performance car will finally be heading to showrooms by the end of this month. According to British automotive magazine Autocar, Fisker’s first customer will be actor and committed environmentalist Leonardo DiCaprio, with Al Gore and Colin Powell set to follow. Just five Karmas will be built per week at Fisker’s assembly plant in Finland until November, when production is expected to increase to 300 units per week. Three thousand pre-orders for the car have been tallied, so Fisker expects all Karmas to be accounted for until…