It's actually a bit of a catch-22....
An obese person has a lot of extra padding. If they get in an accident, they have lots of extra cushion to absorb the energy of the impact (ignoring, for a moment, what happens when their car gets crushed and they can't get extracted w/o the Jaws of Life because they are too large). They often drive larger SUVs because they like the extra room.
So, we are telling them to lose weight.
However, we are also telling people to stop driving heavy SUVs because they pose a higher risk to hurting people if they get in accidents with smaller, lighter cars.
The solution? Restrict SUV sales to those who have 10% or less body fat, since they need the most protection in an accident. Leave the obese people with 30% or more body fact to the skimpy gas-sipping cars that will barely allow them to get 1 leg in, let alone their whole body.