Tesla Motors Club
It appears "What Car?"'s "Real Range" test is ironically named.
Real World Range Test Ranks 10 Popular Electric Cars: Kona Electric #1
Methodology here: (hint, it's flawed, not surprisingly)
What Car? Real Range: how we work it out
In short, the issue with the methodology I see is:
They assume charging efficiency is the same over the entire SoC range. Of course it's not. Basically they discharge the battery completely, measure the amount of energy to fill it. Then they discharge the Model X battery by about 15% (I really don't know the length of their test, but it's relatively short), and then recharge it, measure that energy. They then extrapolate that to the full charge to see how much of the battery charge they used. Such a bad test methodology but at least they were transparent.
There is nonlinearity due to static charging losses, there is non-linearity due to rebalancing, etc.
In addition, they also left the car plugged in overnight, so there may have been vampire losses that were not recharged overnight (it would be random depending on whether the car topped up or not). Those would be amplified by the full charge to partial charge ratio.
Anyway, that's some the reason for the massive "miss" here on range. It may well be that the Tesla falls short relative to other vehicles, but really all they tested was the efficiency of charging the Model X at the high end of SoC.
Just FYI.
Journalists are not engineers, that is for sure!
Real World Range Test Ranks 10 Popular Electric Cars: Kona Electric #1
Methodology here: (hint, it's flawed, not surprisingly)
What Car? Real Range: how we work it out
In short, the issue with the methodology I see is:
They assume charging efficiency is the same over the entire SoC range. Of course it's not. Basically they discharge the battery completely, measure the amount of energy to fill it. Then they discharge the Model X battery by about 15% (I really don't know the length of their test, but it's relatively short), and then recharge it, measure that energy. They then extrapolate that to the full charge to see how much of the battery charge they used. Such a bad test methodology but at least they were transparent.
There is nonlinearity due to static charging losses, there is non-linearity due to rebalancing, etc.
In addition, they also left the car plugged in overnight, so there may have been vampire losses that were not recharged overnight (it would be random depending on whether the car topped up or not). Those would be amplified by the full charge to partial charge ratio.
Anyway, that's some the reason for the massive "miss" here on range. It may well be that the Tesla falls short relative to other vehicles, but really all they tested was the efficiency of charging the Model X at the high end of SoC.
Just FYI.
Journalists are not engineers, that is for sure!