Adds CEO comments, details, shares and background in paragraphs 2, 6, 7, 10-15

By Akash Sriram, Abhirup Roy, Juby Babu

May 6 (Reuters) - Electric vehicle makers Rivian RIVN.O and Lucid LCID.O warned of higher costs from U.S. tariffs on imported vehicles and auto parts, even as automakers scramble to rework sourcing of critical supplies and minimize disruption.

The specter of tariffs comes amid already slowing EV sales as economic uncertainty sours sentiment for consumers, many of whom are avoiding buying cars or choosing cheaper hybrid vehicles instead.

Rivian CEO RJ Scaringe told Reuters the cost per vehicle was expected to rise by "a couple of thousand dollars" due to tariffs.

"Customers are hesitant to make large-dollar purchases, and they're more price sensitive than they historically have been," he said, adding Rivian was working on adjusting its supply chain to mitigate tariff costs.

The EV maker is also anticipating a sharper-than-expected fall in 2025 deliveries to between 40,000 and 46,000 units this year, down from its earlier projection of between 46,000 and 51,000 vehicles.

Lucid's interim CEO Marc Winterhoff said the luxury electric vehicle maker was expecting a rise of 8% to 15% in overall costs due to tariffs, without taking into account any mitigation efforts.

Lucid, however, stuck to its production forecast of 20,000 units for the year that Winterhoff said was an already "low-balled" target given the rollout of its new SUV, the Gravity.

Shares of Rivian, known for its R1S SUVs and R1T pickups that start at about $70,000, were down 1.4% after the market close, while shares of Lucid, whose Air sedans start at around the same price, rose 1.3%.

The Trump administration introduced 25% tariffs on imported vehicles and auto parts. Last week, Trump signed two orders to soften the blow, with a mix of credits and relief from other levies on materials.

In the face of uncertainty, several automakers, including Tesla TSLA.O, have also said they were reassessing their full-year targets.

Rivian on Monday said it would invest $120 million to bring its key parts suppliers near its plant in Illinois, as it prepares to produce its smaller, more affordable R2 SUVs next year.

Lucid is gearing up to launch a midsize vehicle as well with a target price of about $50,000 next year. But Winterhoff said Lucid might start production of the vehicle in Saudi Arabia, a major market for and an investor in the EV maker, instead of the U.S., given tariff costs, though that plan was not final.

A successful rollout of affordable vehicles is seen as critical for both EV makers.

Both Rivian and Lucid reported smaller-than-expected losses on an earnings-per-share basis in the first quarter as they doubled down on slashing costs.

Rivian, which is also benefiting from a $5.8 billion software joint venture with Volkswagen VOWG_p.DE, reported a gross profit of $206 million and stuck to its target of modest gross profit this year.

The company, however, increased its forecast for capital expenditures for the year to between $1.8 billion and $1.9 billion, as tariffs hurt its plant expansion costs, from between $1.6 billion and $1.7 billion predicted earlier.

(Reporting by Akash Sriram in Bengaluru, Abhirup Roy in San Francisco and Juby Babu in Mexico City; Editing by Anil D'Silva and Chris Reese)

((Akash.Sriram@thomsonreuters.com; On X as @HoodieOnVeshti; +91-99017-77617;))