Did you mean increase gas taxes? When I look at the gas price breakdown where I am (Michigan, USA), I only see taxes, no subsidies. http://www.michigangasprices.com/tax_info.aspx
Europe has much larger taxes on gas, diesel, and automobiles than in the US, which discourages car use and ownership.
It doesn't really matter where we import our oil from. The world market is interconnected. If supplies drop in Venezuela, Norway, Saudi Arabia, Iraq and Iran, then the demand for oil from Canada will go up worldwide. So it's in our interest to keep the oil flowing from countries other than Canada.
Granted, this is also because many of the cities in those countries are old and weren't designed for vehicles, leading to congestion problems. These areas usually have high densities of people as well.
Probably because the US does not actually subsidize gasoline. So, the first comment is factually wrong.