New York CNN Business  — 

Time is running out to buy the cheapest versions of the Tesla Model S and Model X luxury cars.

In a tweet, CEO Elon Musk said Tesla would no longer take orders for the 75D versions of the two cars starting Monday. The 75D versions have less powerful batteries than the more expensive versions, so they can’t go as far.

The 75D version of the Model S sedan has a starting price of $76,000, and can go 259 miles on a single charge. That’s $18,000, and 76 miles less than the 100D version.

Model X 75D has a starting price of $82,000 and can travel 237 miles. That’s $15,000 and 58 miles less than the 100D.

An even more expensive version of each car can travel longer distances on a single charge and accelerates faster. Various options, including autopilot, can add thousands of dollars to the costs of the vehicles.

Musk’s tweet said that the company will still accept orders for the 75D versions of both cars through Sunday. He gave no reason for the decision.

A Tesla spokesman did not respond to a request for comment.

One reason for canceling the version could be a lack of demand now that the lower-priced Model 3 sedan is more widely available.The least expensive version of the Model 3 has a starting price of $44,000, while the most expensive version has a starting price of $62,000.

“You have two type of customers, those who are price-oriented and those who are not price-oriented,” said Karl Brauer, executive publisher of “The price-oriented customers are probably looking at the Model 3. The not-price-oriented customer is probably buying the more-expensive versions of the Model S or X. So the 75D fell in the weird nether world that it probably didn’t need to sell.”

Tesla (TSLA) has never provided a breakdown as to how many of the different versions of its vehicles that it sells.

Brauer also said that Musk probably wants to free up capacity at Tesla’s plant in California and its battery factory in Nevada to make more of the Model 3’s, especially the even cheaper version of the Model 3 that it plans to start selling in four to six months.

“He feels the Model 3 is the future of the company,” Brauer said. “And he probably makes more profit on the Model 3 than on a lower price Model S and X.”