Tesla Motors' (NASDAQ:TSLA) most recent quarterly shareholder letter, which was released last week, included a number of interesting updates on the fast-growing business. Published just as Tesla announced it was moving its goal to build 500,000 vehicles per year by 2020 to 2018, the letter provides timely insight.

Here are five useful takeaways from the update that investors shouldn't overlook.

Tesla's under-construction Gigafactory, or a factory purposed to eventually produce more lithium-ion battery cells than were produced in the entire world in 2013, is arguably one of the company's most important initiatives. For the automaker to continue to ramp-up production of its vehicles, it will eventually need to rely on in-house production of battery cells in order to fulfill growing demand and to achieve lower costs for its batteries.

Management was optimistic about the factory's progress:

We remain on plan to make the first cells at the Gigafactory in Q4 2016, and we are adjusting our plans there to accommodate our revised build plan.

While production has already started at the Gigafactory, it hasn't yet begun producing batteries at the cell level. Production at the cell level is important, as this is key to maximizing economies of scale at the factory. So, it's good to hear the company is on pace to begin cell production this year.

The Model 3 objective
Still trying to understand how the Model 3 fits into Tesla's business plan, and how the company aims to make it compelling?

Management summed up its goal with its lowest-cost vehicle in two sentences:

Our objective with Model 3 is to create the world's best car with a base price of $35,000, before any incentives, with a range of at least 215 miles on a single charge, and with strong gross margins. We plan to incorporate our best technology into Model 3, yet keep it relatively simple to build at high volume and with high quality.

Model S order growth accelerated
One key concern among investors as Model X production increases is cannibalization of Model S. But, so far, the opposite scenario is playing out, as Model S orders continue to grow.

Model S. Image source: Tesla Motors.

Q1 Model S net orders rose 45% compared to a year ago, and grew at a faster pace than last quarter. The more rapid pace of growth was driven by increased order growth in North America and Europe, and a more than 160% increase in orders from Asia compared to a year ago. Model S continues to be the market share leader in North America and Europe among all comparably priced four-door sedans.

Management went on to note that new vehicles are actually encouraging Model S sales -- not cannibalizing demand.

Notably, this demand level was reached ahead of the Model S refresh, before Model X could be seen in stores, and prior to the unveiling of Model 3, which we believe is stimulating demand for all of our vehicles.

Production is jumping
In light of Tesla's wildly ambitious growth plans, it's important that Tesla's production continues to rise rapidly. Fortunately, this is exactly what's happening. In Q1, vehicle production hit a record level of 15,510 -- up 10% compared to Q4. And Tesla said it was on pace to produce 20,000 vehicles in the current quarter.

Tesla Fremont Factory. Image source: Tesla Motors.

Further, Tesla anticipates to finish Q2 with a bang.

Importantly, now that supply chain constraints have been resolved, we plan to exit Q2 at a steady production rate of 2,000 vehicles per week, thus laying the foundation for a strong Q3 delivery number.

If this weekly production rate is achieved by the last week of Q2, and maintained throughout Q3, this could mean 26,000 vehicles built during Q3.

Capital expenditures are jumping, too
But rapid growth and bigger plans come at a steep cost.

Given our plans to advance our 500,000 total unit build plan, essentially doubling the prior growth plan, we are reevaluating our level of capital expenditures, but expect it will be about 50% higher than our previous guidance of $1.5 billion for 2016. Naturally, this will impact our ability to be net cash flow positive for the year, but given the demand for Model 3, investing to meet that demand is the best long-term decision for Tesla.

These are just a portion of the insights from Tesla's quarterly shareholder letter. With the company's quarterly earning reports including far more explanations and updates than most publicly traded company's quarterly reports do, its letters are usually worth a read -- and this quarter's letter didn't disappoint.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.