Kylie's rumored boyfriend, rapper Tyga, gave her the white sports car outside the West Hollywood nightclub Bootsy Bellows, where the teen was having her party on Sunday. The lavish car was even decked out like a present with a big red bow.
The gift appears to be a Ferrari 482 Italia, a $320,000 Italian supercar.
Kylie, who covered her mouth in shock at the incredible birthday surprise, was wearing a black sparkly mini dress and her normally dark hair was long and blonde.
The star seemed genuinely overjoyed at the 25-year-old's gesture and was all smiles.
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The Bootsy Bellows event came after a birthday dinner with Kylie's family and friends at The Nice Guy in Los Angeles. The star's sisters Kim Kardashian West, Kendall Jenner, Khloé Kardashian and Kourtney Kardashian were on hand, as well as her parents, Kris Jenner and Caitlyn Jenner.
The family had two tables at the restaurant, with Caitlyn, Kendall, Tyga and Kylie and her girlfriends (including pal Pia Mia) sitting at one, and the rest of the family at the other, according to an observer. Kris' boyfriend Corey Gamble joined her, as well as Kim's husband, rapper Kanye West, and Khloé's rumored new man, NBA star James Harden.
The source tells PEOPLE that Kendall and Kylie, who was wearing a silver, long-sleeved sequin dress for the dinner portion of the evening, spent a lot of the evening popping back and forth between the two tables. Eventually, the family mingled and, of course, took selfies.
"Overall, everyone was in a great mood, smiling and laughing, and just really there to celebrate Kylie's 18th birthday with her," the observer says.
Kendall bopped around as a live jazz band performed, and Khloé slow danced for a moment with Harden, the source says.
The entire group left the venue around 10:45 p.m. through a back exit.
"MY GIRLS," Kylie wrote of a group pic with her friends at The Nice Guy. "Party night. #18@12."
Kim also shared a slew of selfies from the evening, including one with the birthday girl.
"Bad b---- contest you're in 1st place," she wrote.
She also managed to snap a pic of West catching a little snooze at the party.
"Side chicks be like.....part2," she wrote.