If you REALLY want to see the price of gas lowered, there is a simple way to do this.
Do a compromise on keystone, where it is approved, and then 2 limited time subsidies are created for electric cars, and the other for nat. gas commercial vehicles.
We already have large subsidies for electric vehicles, how do you envision these subsidies being different? If you expect the subsidies to get a significant portion of drivers to switch to EV's, how will these subsidies be funded? You've already earmarked the fuel taxes for road repairs.
At the same time, raise federal road taxes on gas/diesel by .25/gal/ year for the next 4 years, and then convert it to a % of the price, with a minimum. Next, give the gas tax to the state in which it comes from, and the diesel tax is used by the federal DOT. Then work on our roads
So add a dollar to the existing 55 cent fuel tax over 4 years, making fuel cost around $4.50 - $5.00 gallon.
By doing this, we will see the tar sands hit global market, raising our local prices. BUT, with the above limited time subsidies, it will move our new vehicles over to none-oil, which will drop demand for gas rather quickly, and then will allow diesel and gas to be around 2/gal.
So we'll pay more for fuel, but fuel will be cheaper? I'm not sure I follow that logic. Also, it's not clear how you'll pay for roads when the fuel tax goes away.
You underestimate how long it would take to switch the USA over to EV's -- even if there was enough world-wide battery capacity to do it (there's not), there would be grid problems -- the grid wasn't designed for everyone to go home and plug in a 6000W charger for 6 hours every night. Smart chargers could help with that by letting the power company control chargers to distribute load, but they aren't here yet, and won't be ready on a large scale in 4 years. If everyone switched to Natural Gas vehicles, then the cost to generate electricity would rise since power companies have been taking advantage of cheap NG to generate electricity
The easiest way to reduce demand is to just tax fuel - don't add $1 in taxes, add $5 in taxes phased in over 10 years. Once drivers are faced with paying $10/gallon, they'll look for fuel efficient commute alternatives themselves (which includes transit (which can be funded from the fuel tax), cycling and moving closer to work, so it will reduce congestion at the same time -- just putting everyone in an EV doesn't help with congestion). Of course, it's not that simple, since drivers know that such a tax would never happen, and they can just vote in someone that will continue to keep fuel cheap.