Took me a little bit of searching to actually find the source, and to call it a study is a bit an overstatement, however here are some links:

https://steinbuch.wordpress.com/2015/01/24/tesla-model-s-bat... [A blogpost about the study]

https://docs.google.com/spreadsheets/d/t024bMoRiDPIDialGnuKP... [The study/survey]

http://www.daglievemensen.nl/tesla/maxrange.htm [Interactive graph]

And as bonus a link to the Tesla Roadster battery study: http://www.groen7.nl/images/wp2013/divers/PIA-Roadster-Batte...