Kasey Kahne said the 'highs' don't outweigh the 'lows' in NASCAR anymore. (AP)

NASCAR driver Kasey Kahne says he is retiring from full-time racing.

The 38-year-old Kahne announced his intentions Thursday on Twitter, saying "I'm not sure what the future holds for me, but I'm at ease with the decision that I have made."

The former Hendrick Motorsports driver has 18 victories in 15 years in the Cup Series, including a playoff-clinching one last season at famed Indianapolis Motor Speedway. That win came amid speculation that Hendrick would part ways with Kahne following six seasons. Hendrick made it official two weeks later.

Kahne signed on with Leavine Family Racing for 2018. He has one top-five finish in 23 starts for Leavine. He had been offered a ride with Leavine next year, but plans to spend his time with his young son, Tanner, and with his sprint car team.

He says "the highs didn't outweigh the lows, and the grueling schedule takes a toll on your quality of life. I need to spend time doing the things I enjoy and love."

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Kahne's announcement came one day after 43-year-old Elliott Sadler walked away from NASCAR after 21 seasons.

Sadler is 43 and currently drives for JR Motorsports in the second-tier Xfinity Series. He spent 12 full-time seasons in the Cup Series driving for Wood Brothers Racing, Robert Yates Racing, Evernham Motorsports and Richard Petty Motorsports. He is retiring to spend more time with his two young children.

They are the latest in a growing list of NASCAR drivers who have hanged up their helmets in recent years, following Danica Patrick, Dale Earnhardt Jr., Carl Edwards, three-time champion Tony Stewart and four-time champ Jeff Gordon.

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