I find the additional weight argument pretty lame considering SUVs and just general size increases have been adding huge amount of weight to cars and noone batted an eye.
Just 30 years ago, the most common cars in Europe, hatchbacks, weighted about 1 ton. Now, the vast majority is SUVs that weigh 1.5-2.5tons, none have lithium batteries.
Oh, and don't get me started on the SUV/pickup craze in the US - look at the weight increase on that vs a European sedan, hatchback or a station wagon - eletric cars are not the problem, this are.
I'm familiar with CAFE standards but US politicians don't seem to have much intent on changing them.
And it is not economically unviable, it is just not as profitable because every other country produces and sells properly sized cars with a profit (except maybe Australia).