Kylie Jenner and Kendall Jenner had quite the "day off" on Tuesday

By Dave Quinn
March 14, 2018 09:44 AM

Kylie Jenner and Kendall Jenner‘s “day off” may involve comfortable clothing, but it’s still glam.

The Keeping Up with the Kardashians stars spent part of the day lounging in matching black robes and slippers on Tuesday — not on the couch or by the pool, as one would expect, but by their tricked-out Mercedes-Benz G-Wagon.

Kylie documented the chill session on Instagram, of course. In the photo, the new mom leaned against the door of the car — her black tank top peeking out of her robe as she gazed up at sister Kendall, who posed on the vehicle’s hood and windshield.

Fans of Kylie know the cosmetics maven has a thing for cars.

The youngest KarJenner — who gave birth to daughter Stormi on Feb. 1 — made headlines last month when she and boyfriend Travis Scott stepped out for a lunch date with friends and family in her extravagant push present: a black Ferrari LaFerrari with red interiors and butterfly doors. (The model starts at $1.4 million and is no longer in production, according to Car and Driver magazine.)

On Tuesday, the 20-year-old again showed off the tricked-out ride while picking it up from the car shop. “Picking up my new bitch,” she captioned the photo.

RELATED VIDEO: What the Kardashians Really Think About Kylie Jenner’s Over-the-Top Push Present

But while the budding car enthusiast is enjoying her new wheels, a source previously told PEOPLE her famous family didn’t exactly warm up to the lavish hybrid sports vehicle.

“Everyone thinks it’s the most ridiculous ‘gift’ ever,” said the source. “[Kylie] has been obsessed with cars for a while. It’s just a status thing. She gets a kick out of the fact that people will stare.”

“Her family thinks she should tone down things a tad,” added the source to PEOPLE. “She is obviously still very immature when it comes to certain aspects of her life, but she’s a great mom.”