Eh, there is nothing stopping manufacturers producing model ranges that average 80mpg, if that is what they want to do. Or full EV. Or whatever. You don't need any agreements with governments or other manufacturers to do these things, unless you think you cannot make any money off it, and have to be authoritarian towards business competitors to prevent them destroying you in the free market by building vehicles that consumers actually want to buy.
It's also somewhat amusing that the agreement they signed appears to be softer than what it is supposed to replace.