Shares of the Lordstown, Ohio, company at last check were down 9.7% at $9.05.
Official results from organizers of the Score San Felipe 250 show that the Endurance Entry reached 39.8 miles of the 280-mile course. The Endurance has a range of 250 miles, according to Lordstown's website.
Out of the 270 entrants, just 187 were able to finish.
"We knew this was a grueling environment and would push us," the company said in a Facebook post. "We successfully navigated the extreme conditions over the first 40-mile leg of the race with all of our mechanicals meeting or exceeding our expectations."
While the company said it "anticipated significantly higher energy demand from this environment – the reality of the terrain proved to be even more demanding."
Lordstown said data indicated that during the race energy consumption was higher than expected and "could result in our vehicle stopping in the middle of mountainous terrain with no viable or accessible charging options."
"The Endurance’s hub motors, battery pack and software performed very well today," the company said, "and everything we did and experienced in Mexico has provided us with valuable insights into how the Endurance’s technology performed and responded to the demanding and treacherous conditions."
"The lessons learned in the desert will become part of the Endurance’s DNA, and help us to meet the rigorous performance expectations and requirements of our customers," the posting said.
Last month, Lordstown Motors reported a wider loss, as had been expected, for the fourth quarter and disclosed a Securities and Exchange Commission probe arising from a short-seller's critical report.
The company was the target of a scathing report by investment research firm Hindenburg Research that called Lordstown "an electric-vehicle SPAC with no revenue and no sellable product, which we believe has misled investors on both its demand and production capabilities.”
The developments have sparked several class-action lawsuits against the company.
Separately, Tesla shares dropped Monday after one of the electric-vehicle maker's cars, believed to be without a driver and on autopilot, crashed, killing two passengers.