The i3 will tip the scales at 2,755 pounds, while the i8 will come in under 3,300 pounds. While that might sound slightly chunky, consider that the average gasoline-powered car converted to EV duty normally tacks on around 500 pounds courtesy of the battery, motor and cooling system. When looked at in this way, both models could be considered rather svelte. The carbon fiber “Life” structure that envelops the i3′s passengers is so strong (yet very light) that BMW's engineers didn't have to include a B-pillar for structural rigidity.
2DayBlog.com, Technical details of the new 'i' cars from BMW