Out of curiosity, today I looked at a comparison of EV vehicle weight to battery size for a few EVs. I'm not sure it means a whole lot, but I found it interesting and thought I would post here before I delete it from my mind and computer. Model Weight (lbs) Battery (KWh) lbs/KWh Tesla Roadster 2690 53 50.75 Tesla Model S (85) 4647 85 54.67 Tesla Model S (60) 4464 60 74.40 Mercedes B-Class 3164 36 87.89 Tesla Model S (40) 4464 40 111.60 BMW i3 2800 22 127.27 Chevy Spark EV 2989 21 142.33 Nissan Leaf 3422 24 142.58 Ford Focus EV 3640 23 158.26 Mitsubishi i-MiEV 2579 16 161.19 I'm not certain on the numbers. Most weights came from stats on the Motor Trend website, with the exception of Model S 40 and 60 weight, which I found on a post on this site. Battery size stats came from various sites. List is sorted lowest to highest on lbs/KWh. Feel free to indicate corrections.
The weight of the BMW i3 (without the range extender) is 2,635 lbs (1,195 kgs): BMW i3 : Technical data