Not sure if you've noticed, but The Atlantic has started a new site called CityLab, which has been producing all sorts of interesting articles on issues faced by US cities and states. The article of interest today discusses how many states' gas taxes are at record lows. And, yes, Utah is one of them. I'll keep this brief, but this following chart shows how Utah's gas tax today compares with what it was in 1927.
It turns out Utah's gas tax in 1927 was twice what it is today (!), after adjusting for inflation. And in 1927 we didn't know that air pollution kills ~94,000 people per year in North America, that climate change may threaten our way of life, that living at lower density makes us poorer and less productive, and that driving makes us fat. We could discourage all of these things with a higher gas tax.
In addition, Utah is facing a $15 billion shortfall in its transportation budget over the next 30 years. See page 32 of Utah's Unified Transportation Plan for more. So it appears that a higher gax tax would be extremely helpful in that realm too.