I would very much prefer free market forces to change people's minds about buying huge SUV's than government influencing the market with some kind of a tax.
If the availability of oil weakens, the price will go up. If it goes up high enough, people will change their spending habits. There is no need for government to intervene.
Current: 2015 i3 REx | Giga | Ionic Silver Metallic
2013 550i xDrive M Sport DHP | Jet Black | Venetian Beige | Dark Red Sycamore
2008 535xi Sport | Jet Black | Cream Beige | Burl Wood