I’m not sure it’s bad policy.
When they first started 10% ethanol and I got a > 10% drop in fuel mileage it seemed nonsensical. But then I got a more recent car and I don’t see a large difference in mileage.
So if ethanol helps us stretch our oil supplies, then great.
If oil is a finite resource then the policy makes sense.
If it’s a renewable resource then it might still make sense depending on the speed which the earth renews it.
Nicolas Loris is an economist at the Heritage Foundation:
https://www.downsizinggovernment.org/ethanol-and-biofuel-policies