Tesla Motors Inc (NASDAQ:TSLA) has surprised again and again over the last year or so. Today shares are up 5% as the date of the company’s next earnings report approaches. In fact, shares are only about $10 below their previous high. But will Tesla surprise in its earnings report again? Nickey Friedman of The Motley Fool thinks the automaker has dropped enough clues that figuring out what that report will say is a cinch.

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Calculating Tesla’s earnings from delivery numbers

Of course there are a few main numbers you must know in order to calculate any company’s earnings, and Friedman was able to derive estimates based on what Tesla Motors Inc (NASDAQ:TSLA) has sold us so far. The four numbers are sales, overhead, interest, and research and development expenses, and gross profits.

She starts with $2.2 million in interest expenses (using non-GAAP numbers), which is how much Tesla spent on it in the previous quarter. Then she looked at vehicle deliveries, which we already know was 6,900 during the December quarter. Of course you need to know the averages selling price to determine revenue, and she used the number from last quarter, which was about $109,600. CEO Elon Musk did say average selling price was roughly flat from the third to the fourth quarter. Based on that average selling price, we see $756 million in revenue.

Determining Tesla’s gross profits, expenses

Tesla Motors Inc (NASDAQ:TSLA) was aiming for a 25% gross margin for the fourth quarter, which means that gross profits would be about $189 million. From that number, we take out expenses. Tesla said it expected a 25% increase in research and development costs for the quarter, plus a 20% increase in overhead. This brings these amounts to about $60 million for research and development and $80.4 million for overhead, using the third quarter numbers.

Then subtract the $2.2 million in interest from gross profits as well, and we have $46.4 million in earnings. With 139 million shares, Tesla Motors Inc (NASDAQ:TSLA) could post at least 33 cents per share in earnings, according to Friedman’s estimates.  She notes that Tesla could have decided to spend more on research and development or speed up the pace of its Supercharger build-out, which would affect the final results.

Tesla heading to reasonable valuation?

Investors and analysts have been locked in heated debates about Tesla Motors Inc (NASDAQ:TSLA)’s valuation for some time, and Friedman thinks the automaker might already be approaching “reasonable valuation territory.” She said with a $170 share price, the price to earnings ratio is still high at 129, but it’s better than 354 which was last quarter’s ratio.

The only problem with this is that should Tesla Motors Inc (NASDAQ:TSLA) significantly surprise again this time, shares could skyrocket even further than current levels, which are already approaching their record high. And 33 cents per share in earnings would be a major surprise in spite of the higher delivery number because consensus estimates show expectations of just 18 cents per share in earnings for the quarter.