[Retric]

Annual road subsidies are around:

(~3 trillion miles / year) / (~300billion / year) = 10c/mile or around 3$ per gallon of gas.

Amtrak = $210.31 per passenger per 1,000 miles = 21c/mile but there are significant network effects so some routs are far more subsidized than others.

And with such a long history of investments in cars and roads it's hard to calculate what's the better long term value.