For Tesla (TSLA -3.55%) shareholders it's definitely great to see the company's vehicle deliveries growing as fast as they are. The electric-car maker's new car sales are up about 57% in the trailing-12-month period. Growth helps solidify the company's lead in long-range, fully electric cars and it gets it closer to a level it can begin to reap the benefits of the scale that comes along with higher-volume production.

Model X production. Image source: Tesla Motors.

But, in the meantime, it's not easy. Rapid growth for a new entrant in a capital intensive, highly competitive industry comes at a high cost: years of losses. This financial stress is why investors should check in on some of the company's key financial metrics every quarter to gauge whether or not its finances are improving.

Here are two metrics for investors to examine when Tesla reports first-quarter results next week that will help provide a window into the company's financial situation.

Operating cash flow
As Tesla's sales grow, investors should look for the automaker's operating cash flow to improve. A trend of improving operating cash flow can relieve concerns that the company's operations might not benefit from operating leverage as sales increase.

Importantly, Tesla's operating cash outflows improved in Q4 to $30 million compared to outflows of $86 million in the year ago quarter. This is also a huge improvement sequentially. In the prior quarter, Tesla's operating cash outflows were $203 million.

Given that the company's total vehicle deliveries actually decreased sequentially between Q3 and Q4 as the automaker focused on problems associated with ramping up production of its new Model X, it's unlikely operating cash flow will improve on a sequential basis this quarter; but investors should look to see if the company's operating cash outflows at least improve on a year-over-year basis, since first-quarter deliveries were up about 48%, year over year. In the year-ago quarter, Tesla's operating cash outflows were $132 million. 

Gross profit margin
Overall, investors should look for Tesla's gross profit margin to improve, too.

In Q4, the company faced challenges with the costs of getting its vehicles to customers, as they were negatively affected by lower-than-expected Model X production.

These margin measures were burdened by $67 million non-GAAP ($51 million GAAP) of unfavorable labor and overhead allocations associated with lower than planned Model X production volume, and non-recurring asset impairment charges for obsolete painting equipment and Model S components as we transitioned to improved production processes and designs.

Model X. Image source. Tesla Motors.

With unexpected problems with Model X production again hindering Q1 production, it's likely Q4's "unfavorable labor and overhead allocations" will persist into Q1. Tesla's gross profit margin, therefore, probably won't improve much -- if at all -- in Q1 compared to Q4.

But I'll still be hoping for a slight sequential improvement in the metric despite production issues. Even though Model X production lagged the company's goals in Q1 as was the case in Q4, deliveries of the newer vehicle increased significantly -- from a few hundred in Q4 to 2,400 in Q1. While a sharp sequential decline in Model S deliveries will negatively impact gross margin, much higher Model X production means the newer vehicle's heady initial production costs may have begun to scale slightly.

In Q4, Tesla's automotive gross margin was 20.9% on a non-GAAP basis and 19.2% on a GAAP basis. So, I'll be looking for a slight sequential improvement.

Other items to watch
For a look at other items to watch when the company reports first-quarter results, including guidance, Model 3 production ramp plans, and Tesla energy, check out this article.

When it comes to the company's closely watched revenue and non-GAAP EPS metrics, my expectations are in line with the consensus analyst estimate for revenue and non-GAAP EPS of $1.6 billion and a loss of $0.57. These results compare to year-ago revenue and non-GAAP EPS of $1.1 billion and a loss of $0.36.

Tesla reports results on Wednesday, May 4, after market close.