That's like the hall of fame entry for things that aren't actually true about electric vehicles. Efficiency doesn't get worse at highway speeds as compared to gas engines. EVs and gas engines spend more of their energy going faster against air resistance. evs are vastly more efficient than gas cars in terms of energey efficiency, thats why electric cars have theoretical gas mileage of around 100 mpg. But gas is a very efficient energy storage mechanism, gas cars are about 1/4 the efficiency of electric cars but can be gased up quickly and have more net range usually.

Teslas don't lose half their range when it's cold. They do lose some range, but it's much less than other evs, because they heat up the pack. evs are great for cross country travel, if there are reasonable charging stations along the way (which is best with tesla).