Andrew W.K. has done a lot of unusual things in his career -- not everyone can have a Cartoon Network show and be a member of Current 93 (not to mention run a club, release an album of J-pop covers, and publish a book of advice) at the same time. Still, 55 Cadillac may be one of the most unique additions to his body of work: it's a collection of "spontaneous solo piano improvisations" -- or "SSPIs" as W.K. calls them -- inspired by his car. It's also, like most of his projects, kind of ridiculous and kind of amazing. He's completely committed to the concept, and he has the skills to pull it off. After all, W.K. is a classically trained pianist who began taking lessons at age four, and his keyboard chops added fizz to I Get Wet and Close Calls with Brick Walls and majestic heft to The Wolf. That prowess is the focus of this album; on his Steinway & Son Model D concert grand piano, Andrew W.K. weaves classical, jazz, rock, and experimental elements together with an accomplished ebb and flow from piece to piece and within each track. The fantastically named "Begin the Engine" (why merely start an engine when you can begin it?) is overtly classical-influenced, kicking off with the sound of crickets and a motor roaring to life before W.K.'s dazzling arpeggios and otherwise deft playing take over for nearly nine minutes. Shorter tracks like "Seeing the Car," which tosses hints of '50s-style rock into the mix, and the lunging, jazzy "Central Park Cruiser" are more immediate and nearly as impressive. Only a couple of moments on 55 Cadillac sound anything like Andrew W.K.'s previous albums: "Night Driver" ranges from atonal boogie-woogie to W.K. tapping on the piano's edge (which might be the piano equivalent of a drum solo) and has an anthemic quality that's fully realized by "Cadillac," which boasts drums and laser-guided guitars that bring the album to a satisfyingly over the top close. Fans of his louder music might not play this often, but 55 Cadillac is another step toward Andrew W.K. putting his stamp on every art form.