GP is likely talking about US federal gas taxes -> Highway Trust Fund -> Federal highway spending.
Notably, though, the HTF spends more than it earns in gas tax revenue; the shortfall comes from the general fund. And also Federal highway spending does not cover all highway spending; the rest comes from the states[1][3]. Federal highway spending also does not cover local roads at all.
[1]: https://www.cbo.gov/sites/default/files/images/full-reports/...
[2]: (Above image from https://www.cbo.gov/publication/57138 )
Do you have any sources for that? I'm in Australia, where fuel costs about twice what it does in the US. A decent portion of that is taxes/duties, but road spending is taken from consolidated revenue, and fuel taxes ultimately contribute a minority of the spending on roads. So unless the cost of fuel production is massively lower in the US, something doesn't add up.