> and lead was standardized only because it was patentable

That doesn't make much sense to me. It would be more profitable to sell gasoline without lead tetraethyl because you wouldn't be forced to buy a patented product. Just pour a shot of pure grain spirit in your tank on every refill (or however much is needed).

It's more plausible that engine technology today has improved to the point that ethanol alone can eliminate knocking.

The link you provided gives more context.

> One already-known remedy was replacing a substantial proportion of the gasoline fuel with ethanol – though ethanol’s lower energy content made the engines less efficient...[General Motors and Standard Oil] claimed that ethanol – often used in automobile fuels before the war – was an unsatisfactory alternative.

and

> Unless the fuel producers themselves get into this work of investigating the properties of their fuels, there is a good chance that they may have to pay tribute to others

Translation: anti-knock compounds was a good business for Standard Oil to be in themselves. Instead of paying another company for a patented product.