Doesn't sound like you know much about how any of this really works. A increased gas tax (or tax direct on oil) would spur new research for other forms of transportation and research for alternate energy sources even if not one penny of the collected tax went to pay for that research. That is it could be used to pay nations current bills instead of shamelessly making future generations pay those bills and at the same time encourage research in alternate fuels.
Your information on where the gas tax is currently being spent is wrong also. The current tax on oil in the US is much lower than Europe or Japan and it is designed to facilitate one thing - use of oil. And right now every penny of the tax goes to subsidize oil powered transportation and nothing else. Currently the gas tax is way too low to even fully fund the maintenance of the nation's highway system as a result much of the money spent on highways is now coming out of general revenue funds.
-jim