Where did you get the 2% figure from? The EPA says "[t]he national benzene content of gasoline today is about 1.0 vol%"[0]. Not that 1% is much better but I'm still curious where your figure comes from.
Benzene is a bit denser than gasoline, so volumetric vs mass vs molar basis aren’t directly comparable. This EPA slide deck [0] has ~1.25% by volume equated with ~1.5% by mass towards the conclusion slide. Interestingly it used to be around 5% benzene by volume before the newest standard.
So 2% on a molar basis doesn’t seem obviously inconsistent with 1 vol%
So 2% on a molar basis doesn’t seem obviously inconsistent with 1 vol%
[0]: https://www.epa.gov/sites/production/files/2021-03/documents...