The average car purchased in 2023 emits higher levels of carbon dioxide (CO₂) than its 2013 equivalent. This is due to the large proportion of SUVs in the mix, which tend to be bigger and heavier.
There's a video that the longer the wheelbase of the vehicle the less stringent it has to be on fuel economy. Something about the 2008 or so cafe laws. Lots of older cars without direct injection get better fuel economy than newer ones that are just taller with the same interior capacity.
The car market isn't like the smartphone market though. These manufacturers don't build a one size fits all model to release worldwide, they build specific models for each market that sometimes overlap with other market models but more often dont.
The first widespread introduction of catalytic converters was in the United States automobile market. To comply with the U.S. Environmental Protection Agency's stricter regulation of exhaust emissions, most gasoline-powered vehicles starting with the 1975 model year are equipped with catalytic converters.[1][
One of CARB's responsibilities is to define vehicle emissions standards. California is the only state permitted to issue emissions standards under the federal Clean Air Act, subject to a waiver from the United States Environmental Protection Agency. Other states may choose to follow CARB or the federal vehicle emission standards but may not set their own.[2]
Yes while CARB may effect other vehicles sold in the US (the same market), it doesn't necessarily effect cars sold in other markets on the other continents. As I said, they generally build different cars for each market which is why Europe gets so many diesels, Australia gets Utes, the US gets SUVs in all flavor, etc.