I’m not the biggest fan of it either, I only mentioned it as an example that some people will willingly destroy their own cars for a small incentive. I recall it shrunk the used car market noticeably, which had the effect of raising the price of transportation for people who couldn’t afford new cars.

Had it been crafted with lower emissions as the end goal instead of economic stimulus, such as the credit only applying to only the most fuel efficient vehicles from each brand, it could’ve had a larger positive effect. It wasn’t a complete waste, though. Taking the most fuel inefficient vehicles off the road, even when replaced with a modest improvement, can have a profound difference, since MPG is a not linear decrease in gas usage.

The alternative bill described in the wikipedia article that some democrats proposed would’ve done more good, especially as it would’ve given $1,000 toward purchasing a more fuel efficient used car as well.

Destroying the car (or at least the engine) isn’t entirely out of the question, as that has successfully happened when incentives are given, such as with the cash for clunkers program. But I can’t imagine that would be a better option emissions-wise compared to EV conversions.

Perhaps subsidizing EV conversions could be a viable route. A significant tax break and perhaps government loans for newly formed conversion companies could really ramp up scale of conversions, and hopefully lower costs.

Ideally, even larger tax breaks could be offered to worker coop conversion shops to encourage that form of business.

Since these won’t perform as well as a purpose built EV, as another user mentioned, owners will likely want larger batteries to compensate. If done at scale with lithium based batteries, that would be both costly, and worse, terrible for the environment due to the requirements for lithium.

Sodium ion batteries are just about production ready, and would be the environmental material of choice if this were to be done, even if their range would be lowered due to the decreased energy density.