EPA mileage ratings, gas, diesel, and electric are all submitted by the manufacturers themselves. Sometimes if the car is similar enough to another car (Toyota Avalon and Camry) they won't even test it and just give it the same number.
Mercedes' worst car only gets 3% over the published range. Most Porsche's are above their range.
Tesla's best vehicles are only 20% below their rated range. The worst Teslas are 30% below their stickers. Easily the worst in the entire industry. Their average for the BEV industry is 13% below the sticker range. So Tesla is 2-3x worse than average.
For comparison against gas vehicles. Across all of their tests, ICE vehicles tend to perform 4% better than their sticker.
I wish EVs would prominently also publish their efficiency (miles/kw). MPGe isn't a useful value for an EV. My Bolt has a 60kw battery, depending on my driving I get between 3.5 to 4.5 miles per KW - 210-270 miles.
This notion that your car gets 240 miles, even if the conditions are adverse, is silly. Gas cars are impacted by cold weather too. My car got 20% worse gas mileage in the winter when I lived in the Midwest. If you drive really fast you won't get as good of range out of tank as if you drive slower.
Car and Driver have a very thorough breakdown of published range versus their "real world 75mph highway test". https://www.caranddriver.com/features/a44676201/ev-range-epa...
Mercedes' worst car only gets 3% over the published range. Most Porsche's are above their range.
Tesla's best vehicles are only 20% below their rated range. The worst Teslas are 30% below their stickers. Easily the worst in the entire industry. Their average for the BEV industry is 13% below the sticker range. So Tesla is 2-3x worse than average.
For comparison against gas vehicles. Across all of their tests, ICE vehicles tend to perform 4% better than their sticker.