The higher Tesla Motors Inc (NASDAQ:TSLA) shares go, the longer the debate lingers. How much is the company really worth? Seeking Alpha contributor Gregor Hill explains the bear case yet again, and of course he recommends shorting it, although not necessarily right now, even though others say that even shorting it sounds logical, it could still be very risky to do so.

Tesla Motors

Tesla’s fundamentals

As all bear cases are, Hill’s case is based on fundamentals, although he does note that Tesla Motors Inc (NASDAQ:TSLA) is a growth stock. Of course he compares Tesla’s PE ratios to those of other automakers. Investors are paying PE ratios between 7 and 12 for established automakers, although they’re paying about 290 for Tesla based on the company’s estimated 2013 earnings.

In terms of enterprise value / revenue multiples, automakers tend to be around 1, although Tesla’s is 9.6 based on this year’s revenue projection. There’s certainly no denying that these numbers are exceptionally high, and according to Hill, investors are overlooking the need to see “the achievement of a reasonable valuation level within a foreseeable timeline.”

Under his estimates, Tesla Motors Inc (NASDAQ:TSLA) needs to hit $1.3 billion in earnings at the end of “the applicable time period,” which he set at three, five and 10 years in three different scenarios.

When Tesla would be a “worthwhile investment”

According to his calculations, with a “reasonable 6% – 7% net profit margin,” Tesla Motors Inc (NASDAQ:TSLA) must achieve yearly growth rates at 71 to 77 percent over the next five years in order for it to become a “worthwhile investment.” That assumes an annual share price return of 10 percent.

In the three-year scenario, the EV automaker would have to achieve 131 to 143 percent annual growth, while in the 10-year scenario, the company would have to achieve between 37 and 39 percent growth annually.

As of this writing, shares of Tesla Motors Inc (NASDAQ:TSLA) were up 1 percent.