Electric-car maker Tesla Motors Inc. has begun selling used versions of its Model S electric cars on its website, an important step for the luxury car maker as its business matures.

Its certified vehicle program, which Tesla launched without fanfare late last month, allows buyers to obtain Tesla’s cars at a lower price than its new vehicles, and comes with the manufacturer’s maintenance and reliability checks. Like other luxury car makers, Tesla offers a 4-year or 50,000-mile limited warranty on its used cars.

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