If I'm reading this report correctly[1], California's car registration fees and gas taxes cover more than the cost of roads. Caltrans estimates $20.2 billion in revenue from fuel taxes and vehicle registration fees, while their budget is $18.7 billion.
It also looks like public transportation is mostly paid for with sales taxes, federal loans/grants, and $1 billion of taxes on diesel fuel.
1. See chart A on page 24, and chart F on page 28: https://dot.ca.gov/-/media/dot-media/programs/budgets/docume...