There has been some discussion about CAFE (Corporate Average Fuel Economy) standards, after I quoted the Hyundai Motor America CEO as saying that CAFE is the main reason they are pursuing a V6 twin-turbo.
One thing I found out doing a little research is that the CAFE fines, currently $5.5 for each 0.1 MPG over the standard, are for the entire fleet, not just those cars which exceed the standard. The CAFE number has to be achieved as an average for all cars that are sold in the US by a particular manufacturer. So if Hyundai was 1 MPG over the standard, and if they sold 700,000 cars per year in the USA (as they did in 2014), they would have to pay $38.5 million in fines.
MB has paid the fine for their entire fleet, about $120 per car. In the future they may not be able to pay the fine, but "may" have to purchase credits from other manufacturers who are under the CAFE standard.
CAFE standards will be rising steadily over the next 10 years. For 2015, a car the size of MB S Class must have an average MPG of 23 MPG (EPA Window Sticker average MPG) to avoid fines. By 2018 that will be 26 MPG, and by 2025 it will need to be 34 MPG average.
A small car the size of a Honda Fit currently must average 29 MPG EPA average, by 2018 34 MPG, and by 2025 43 MPG.
Gas guzzler taxes are only paid on those cars which exceed the limits for that tax (not the entire fleet).