Plus, the 'Late Late Show' host poses with Jennifer Lopez before they debut their new segment.
Surprisingly, James Corden didn't bust out his best J to the L-O for this preview.
The comedian is celebrating his one-year anniversary as Late Late Show host with a primetime special, aptly titled The Late Late Show Carpool Karaoke Primetime Special, featuring some of his best karaoke segments -- Adele, One Direction, so on and so forth -- and a new session with Jennifer Lopez.
But in this hilarious preview, Corden busts out his best Macklemore impression, changing the lyrics of "Downtown" to celebrate his primetime debut and remind himself to clean up his language for the earlier time slot.
WATCH: Justin Bieber and James Corden Perform Bruno Mars Cover in Third 'Carpool Karaoke'
"I have loved every minute of hosting the Late Late Show. It's been an incredible year," Corden has said of the special. "I look forward to this hour on primetime to look at some of my favorite moments and share a couple of great new ones. I can't wait!"
And we cannot wait to see what he gets Jenny from the block to sing.
As for Corden's dream Carpool Karaoke guests, he hasn't managed to get them into his passenger seat just yet. The comedian told ET he wants Bruno Mars and Jay Z to join him -- or Cap'n Geech and the Shrimp Shack Shooters from the 1996 movie, That Thing You Do!
The Late Late Show Carpool Karaoke Primetime Special airs March 29 at 10/9p.m. on CBS.
Relive our personal favorite Carpool Karaoke yet: James Corden and Adele! Watch her epic Nicki Minaj rapping in the video below.