The author makes the assertion that the mpg targets are easier and it's implied it's because the number is lower. I'd like to see that assertion actually suppo

The author makes the assertion that the mpg targets are easier and it's implied it's because the number is lower. I'd like to see that assertion actually supported with evidence. Making a heavier car, with higher ground clearance, and a less aerodynamic shape (squared rear) means it will get less mpg by default. So what makes it easier to hit the mpg target vs a sedan?