According to the latest data from the European Automobile Manufacturers Association (ACEA), sales of Electrically Chargeable Vehicles (which include plug-in hybrids) in Q1 of 2017 were brisk across much of Europe: they rose by 80% Y/Y in eco-friendly Sweden, 78% in Germany, just over 40% in Belgium and grew by roughly 30% across the European Union... but not in Denmark: here sales cratered by over 60% for one simple reason: the government phased out taxpayer subsidies.

As Bloomberg writes, and as Elon Musk knows all too well, the results confirm that "clean-energy vehicles aren’t attractive enough to compete without some form of taxpayer-backed subsidy."

The Denmark case study is emblematic of where the tech/cost curve for clean energy vehicles currently stands, and why for "green" pioneers the continued generosity of governments around the globe is of absolutely critical importance, and also why Trump's recent withdrawal from the Paris Climate Treaty is nothing short of a business model death threat.

To be sure, Denmark's infatuation with green cars is well-known: the country's bicycle-loving people bought 5,298 of them in 2015, more than double the amount sold that year in Italy, which has a population more than 10 times the size of Denmark's. However, those phenomenal sales figures had as much to do with price and convenience as with environmental concerns: electric car dealers were for a long time spared the jaw-dropping import tax of 180 percent that Denmark applies on vehicles fueled by a traditional combustion engine.

Then, in the fall of 2015, everything changed: that's when the government of Prime Minister Lars Lokke Rasmussen announced the progressive phasing out of tax breaks on electric cars, citing budget constraints and the desire to level the playing field. In retrospect the "leveling" effectively nuked the market: the chart below shows the total collapse in sales following the elimination of subsidies.

Nobody was hurt more than Tesla: the company, whose sales were skyrocketing at the time, lobbied against the move, with CEO Musk warning during a visit to Copenhagen that sales would be hit. It wasn't clear if the warning was targeting the government, the people of Denmark, or his own bank account and shareholders, but he was absolutely correct: in 2015 Tesla sold a total of 2,738 cars in Denmark. In 2016 the number dropped by 94% to just 176 units.

The new tax regime "completely killed the market," Laerke Flader, head of the Danish Electric Car Alliance, told Bloomberg.

The punchline: "price really matters." And, by extension, taxpayer subsidies.

What happened next is probably obvious. As Bloomberg explains, while the government’s original plans anticipated to phase out tax breaks from 2016 to 2020, when they would be treated in the same way as fossil fuel-powered cars, on April 18, having taken note of the drop in sales, the government decided to change the rules.

"It’s no secret electrical vehicle sales have been below what we expected a year and a half ago," Tax Minister Karsten Lauritzen said in a statement. "The agreed phase-in has turned out to be hard and that likely halted sales." The new rules mean the transition to a post-subsidy era has been postponed until at least 5,000 new electric cars are sold over the 2016-2018 period. Tax breaks will in any case be progressively eliminated as of 2019, regardless of sales numbers. The plan envisages a 40 percent registration tax minus a 10,000 kroner ($1,500) deduction in 2019, with the tax rising to 65 percent in 2021, 90 percent in 2021 and 100 percent in 2022.

It was unclear if Musk lobbying was behind the parial U-turn, however any hopes for a prompt rebound in sales appear to have been chilled by the Danish government's decision which has "caused confusion, prompting many potential customers to either postpone or desist from their purchases." Meanwhile in generous next door neighbor, Sweden, sales of low or zero emission cars continue to boom thanks to a wide range of subsidies, including a five-year tax break and a 40,000 kronor ($4,600) purchase premium.

According to Flader of the Danish Electric Car Alliance, the Danish electric car industry "doesn't want to invest in a market that may not be there next year. They'd rather invest where conditions are better and predictable long-term." And that means lots and lots of guaranteed taxpayer subsidies. While Flader anticipates a rebound in sales as soon as dealerships are allowed to advertise tax-free prices again, this time the country's raging enthusiasm for all things "green" may be far more muted.

As for Tesla, and its all time high price, what the Danish case study showed just how much of that market cap, which on Friday surpassed BMW, is thanks to government generosity. Take the subsidies away, and sales crash by over 90%.

Should the rest of the world follow in Denmark's example, the same thing would happen to Tesla's market cap, which at last check amount to just over $800,000 per car sold.