What they are trying to do is to restrict/discourage driving.
I'm guessing that they are afraid that people will buy more fuel efficient vehicles and continue to drive more and more miles, and that the gas tax won't be sufficient to discourage that behavior, even if raised.
But they'll never admit that.
If they really want people to drive less miles, they should get serious about encouraging telecommuting for those sectors in which it would make sense.
"What they are trying to do is to restrict/discourage driving"
They know people in California have to drive. It's no more an attempt to restrict/discourage driving than tobacco taxes are an attempt to restrict/discourage smoking.
It's all about the revenue they think they can collect. Nothing more, nothing less.
That does make sense. Of course, if they were really interested in solving traffic problems they'd look at ideas like congestion pricing, rather than charging the same amount per mile during rush hour and at midnight. So it looks like this is a Big Brother program to track us, or an environmentalist wacko social engineering scheme to make us ride bicycles. (And those aren't mutally exclusive).