With the current regulations, it makes the most sense to sell trucks with the longest wheelbase and largest width.
It sounds as though the 'regulations' are preventing US consumers from having a choice in trucks, which.. kinda makes no sense from what I've seen in the wide range of oversized trucks in the US.
Or something along those lines.
This is also why SUVs exist, they are legally trucks for fuel efficiency/etc.
(Quotes because the words refer to the legal definition of trucks/cars.)
In my mind I would like to see the opposite happen, and instead have a review into these "trucks" to see if they are actually what we want for the road.
There's been diagrams produced that through the ages these vehicles have been getting bigger but with less actual cargo space in them. While some in the country might want them I don't believe for a moment they are as necessary nor as useful for the cities and suburbs where parking space sizes would matter.
I want to say there was a Ford which had a fuel port on the rear of the vehicle which had to position the car further forward than usual, blocking the traffic exit while filing up the vehicle.
Now it turns out that making a truck, say, longer by 10% does not increase the fuel consumption by 10%. If you are a manufacturer, you want to maximize the ratio of the allowance based on the square footage divided by the actual measured fuel consumption of the vehicle. The sweet spot comes out on the large side. So the fuel efficiency regulation, ironically, is causing a trend that leads to more total fuel consumption.