R&D, engineering, manufacturing process changes, supply chain changes (I think this pretty much requires hybrid) all the way from mining, etc takes time. The world can't change on a dime.
There's plenty you can change to improve fuel economy without replacing the entire engine design.
Fuel maps (potentially at the expense of power)
Transmission shift maps (at the expense of acceleration)
Lighter materials elsewhere in the car (this one actually is better for performance too!)
Better stock tires
Final drive ratio (again, sacrificing acceleration) or gearing in the transmission if necessary.
Compromises will be have to be made for sure, but they can be spaced out so all the legwork doesn't have to be done at once.
Of course I didn't even mention hybridization because that's not a minor change, but some manufacturers might still opt for it and you could keep the same engine technically.
Those are such small things. Not even sure you can do some because of the way mileage is calculated - pretty sure part of it is "accelerate from this speed to this speed in this time, so many times".
The rules, issued by the National Highway Traffic Safety Administration, call for improvements over a five-year span starting with 2027 models
So they did exactly what you suggested. We also have current rules in place that are increasing fuel efficiency over time. It's not just nothing and then meet this standard by 2031, it's improving by 2% per year, every year, starting in 2027 (the beginning of the time period for the newest set of rules). The article posted is just very light on details. The article is just quoting where they would be at, in 2031, with those yearly goals. So current rules are that cars be at 55 mpg by 2027, and the new rules rate beginning that year, would be 56 in 2028 etc until at 61 mpg for cars in 2032 (and 45 mpg for light trucks)
What targets exactly? Should every policy be limited to just their term? That completely removes the possibility of any target that takes a long time to reach. It would be a waste of time and resources to do smaller increments and then revisit them.
Almost every policy put into place will have effects that future presidents have to deal with. Do you actually care about this in principle or do you just not like this policy?
How do you stay accountable when you don’t set limits in your own term?
You don't. Even if they're in office, there's nothing you can do. What do you think they'd do to Biden? Jail him? Fine him? You vote in people who align with what you want put in place, then have the separate parts of government check each other.
I don’t mind long-term goals, we need them, but there should be milestones
I addressed that in my previous comment. Nobody's wasting time and resources. Such a limitation would cripple every president and make them damn near useless. They'd spend most of their time in office recalculating milestones, which would be incredibly small, at best, and impossible at worst.
frankly I’m surprised it’s apparently an unpopular opinion.
Because it kinda indicates that you haven't really thought about this or you're just not aware of how things happen in life. You're coming off as management that's never worked on the floor and have no idea about what's actually feasible. It's a good way to have everybody despise you.
Using this as an example, let's say it was done at the start of Biden's 1st year, what percentage should he set per what time period, and do you really expect car manufacturers to recreate their vehicles each period?
Manufacturers need time to meet targets. And the final percentage would be incredibly small, because it would be only four years. Whenever you see a product hit the market, development has starts years prior.