To come right to the point, there are Teslas everywhere in Oslo - and I mean everywhere. Norway (with just 5 million people) is the second largest market for Tesla in the world. In fact, Tesla is the number one selling car in this county. No kidding! The Tesla S outsells Ford (every model) here.
Norway is an extremely environmentally sensitive country. I believe they have the smallest carbon footprint per person in the world (if you focus only on consumption). Norway is also an extremely wealthy country. This has made the Norwegian currency very strong. This makes it really expensive for us to visit, and really cheap for Norwegians to travel abroad.
So, here's the first irony: Norway's wealth comes almost entirely from exporting oil and natural gas. Over the years, with prudent planning the government has built up a huge sovereign wealth fund (like the old Alberta Heritage Fund) so it can fund government programs and subsidize behaviour it wishes to encourage.
The second irony is that I've been here 3 days, and I haven't heard anyone say "leave it in the ground (or under the sea)". Unlike Barack Obama's friends who think Canada should be punished for selling our oil and gas, Norway is selling their's as fast as they can - and using the revenue generated to fund public policy objectives like energy conservation (and presumably health care, education, social services and pensions too).
Norway develops, pumps and sells it's carbon-based fuels, while using abundant hydro electricity and lots of money to subsidize environmentally desirable behaviour amongst its citizens. Taxes here are very high on everything, but especially on fuel, cars and roads. However, if you buy an electric car (like a Tesla or Nissan Leaf), you don't have to pay sales tax, you don't pay road tax, you don't pay tolls, and you get to drive in the HOV lanes. You can also write off 100 percent of the cost if you use the electric car for work (which explains the Tesla taxis you see here).
So, after all these incentives are factored in, Teslas don't cost Norwegians any more than other luxury sedans (probably less). By selling huge amounts of oil and natural gas to others (so they can burn it), you get to be seen as a low carbon place. Ironic, isn't it?