I've been driving a EV since
I've been driving a EV since June 2011. I have over 100,000 miles experience driving a 100% BEV. I can promise you unequivocally every pound a EV carries costs some range. Every MPH of head wind costs some range, Every degree of cooled or warmed cabin air above or below the outside temperature costs some range. Every PSI of tire pressure below normal costs some range. EVERYTHING ANY VEHICLE CARRIES OR DOES REQUIRES ENERGY AND COSTS AGAINST THAT VEHICLE'S TOTAL RANGE.
This is true of gasoline and diesel vehicles also. However, the energy density of liquid fuels is much greater than batteries, so the loss of range associated with carrying your fat ass mother-in-law around all weekend is barely noticed. The same is true of battery powered vehicles with a lot of range. But just because it's not obvious doesn't mean the effect on range (and performance) doesn't exist.