General Motors (NYSE:GM) said it delivered 2,052 Chevrolet Bolt EVs in the United States in August. It was the best month yet for the little electric crossover. 

The expectations (and hype) around Tesla's (NASDAQ:TSLA) Model 3 continue to rise, and it's likely that the Model 3's sales will eclipse the electric Chevy's before long. But the Bolt is still the only vehicle seen as anything close to a Tesla rival, and it has now quietly posted six consecutive months of rising sales. 

Tesla will probably be selling tens of thousands of Model 3s a month before long. But GM has always had much more modest ambitions for the Bolt: What's the likely upper limit for the little electric Chevy's sales? 

A black 2017 Chevrolet Bolt EV parked outside on a sunny day with mountains in the background.

The monthly sales totals keep rising for GM's Chevrolet Bolt EV. Image source: General Motors.

Sales of the Bolt have risen steadily for months

Here's a look at how the Bolt's U.S. sales have fared since its launch last December.

A bar chart showing that monthly U.S. sales of the Chevrolet Bolt EV have increased steadily from 952 in February to 2,052 in August.

Data source: General Motors' U.S. sales reports. Chart shows U.S. sales of the Chevrolet Bolt EV by month since its introduction in December of 2016.

That sales increase has almost certainly been driven by increased availability of the Bolt, supply rather than demand. The only dealers certified by GM to sell the Bolt in the first few months it was on the market were in California and Oregon. GM gradually expanded the Bolt's availability to dealers in 21 states over the course of the spring, before finally allowing dealers nationwide to order the Bolt as of June 1.

Of course, there's a time gap between when a dealer places an order and when it receives a car that it can sell. The Bolts ordered in June began arriving on dealer lots last month. That's the simple explanation for last month's sales jump, and it suggests that we could see more incremental increases over the next couple of months.

But given that sales of the Bolt have steadily increased as supplies on dealer lots have increased, what's the true level of demand? Or put another way, at what level of monthly sales will GM decide that the Bolt has been a success? 

The real question may be, "How many can GM build?"

It's still hard to say. GM has said that production and sales of the Bolt are going according to its plan so far. Back when the Bolt was still under development, there were reports that GM was scaling its manufacturing to make about 30,000 Bolts a year once it was fully ramped up. That suggests a planned sales pace of about 2,500 a month, worldwide.

GM isn't far from that just in the United States right now. Now that GM has begun advertising the Bolt, it seems likely that it could sell 2,500 or even more at some point in the next few months.

A white preproduction Chevrolet Bolt EV is shown on the assembly line at GM's factory in Orion Township, Michigan last year.

How many Bolts can GM build? That's an open question, and the answer may depend on the capabilities of GM's suppliers. Image source: General Motors.

I suspect GM could increase production somewhat above that level without too much trouble if demand warranted. In July, it halved production of the (gasoline-engined) Chevrolet Sonic, a small car built on the same assembly line as the Bolt. Theoretically, at least in terms of production-line capacity, it could double production of the Bolt without making other changes. 

That said, it's quite possible that the production abilities of GM's suppliers will turn out to be a constraint on Bolt production in the near term. In particular, the Bolt's batteries, powertrain, and other key systems are supplied by LG Chem, which would almost certainly need time to scale up its production in any significant way. 

Long story short: The Bolt may already be close to sales "success"

I strongly suspect that GM will be pleased if the Bolt can sustain about 2,500 sales a month -- pleased enough to accelerate its development of more electric models. (It may have already made that decision.) 

It's possible the Bolt's sales will never go much beyond that level. (It's almost certain that the Model 3 will outsell it soon.) But the Bolt was never meant to be a true Tesla competitor or a huge-selling retail product: It's GM's way of testing the waters with a product it can use in testing or sell to fleet customers if enough retail buyers don't materialize. (Whatever its merits as a personal car, the Bolt is a great taxi. That's not a coincidence.) 

The good news is that the Bolt appears to have found a (growing) niche at retail. The better news for electric-car advocates is that the Bolt may already be enough of a success to convince GM to bring more electric vehicles to market. That could turn out to be good news for GM's shareholders in time, too. 

John Rosevear owns shares of General Motors. The Motley Fool owns shares of and recommends Tesla. The Motley Fool has a disclosure policy.