Rivian is discontinuing the cheapest trim level of its all-electric truck and SUV known as the Explore package due to low demand, according to emails sent this week to customers.

The company said in the email, which was first cited in the Rivian Owners Forum, that customers with a pre-order for the Explore package will need to reconfigure to the Adventure trim by September 1 or have their preorder cancelled. Rivian also issued information on its customer support page that explains why it cancelled the package and what customers' options are.

For customers who pre-ordered the Explore trim, the change means an increase of about $5,500. The base Adventure package, which includes a dual-motor and standard battery pack that gets more than 260 miles of range, starts at $73,000.

"In order to deliver as many vehicles as possible, we have made the decision to discontinue the Explore Package. We realize this news is unexpected and apologize for how it impacts your plans," the email said.

A few customers on the forum expressed their anger at the changes. It's unclear if Rivian will lose existing customers due to the change. Although with a reported backlog of orders, it may not matter. As of June 30, 2022, Rivian's net R1 preorder backlog was about 98,000 from consumers in the U.S. and Canada, according to its second-quarter letter to shareholders.

The company initially launched its R1T truck and R1S SUV with two packages. The Explore was intended as the entry-level package and the Adventure was the higher-priced trim that offered more features.

Rivian said in the email that it expected a large number of customers would choose Explore. It turns out, they have not.

"To date, only a small percentage of customers have chosen this configuration, with the vast majority selecting the Adventure trim. By focusing on the Adventure trim package, we’re able to streamline our supply chain and ultimately deliver vehicles more quickly," the email stated.