If your pocket’s deep enough, you can probably buy it. (The wheel design puzzles me, though – what’s the function of the one on the top of each “tri-star”?)
The Starship Heart of Gold; “As the ship’s drive reaches Infinite Improbability it passes through EVERY CONCIEVABLE POINT in EVERY CONCIEVABLE UNIVERSE almost simultaneously, you select your own re-entry point, be the envy of other major governments”
this is big league stuff here 
TARDIS and Moya also qualify
IIRC, the whole tri-star revolves and propels the vehicle through water or loose sand.
I think Gay Deceiver is cheating. As a multi-dimensional, self-aware entity, she is more “person” than “vehicle.”
And let’s not forget the Puppeteer Homeworlds. Five planets and a mini star all travelling at a substantial percentage of C.
Not much good for everyday use, but the horsepower sure beats my big block Ford!
There can be no cooler vehicle than the starship Heart of Gold, because it is the ship of the coolest person in existence - Zaphod, he’s just this guy, you know.
I feel obligated to point out that this would also be a point in favor of the Nautilus– aficionados of the movie have noted that there’s really no logical way the various interior sets could have all fit inside the vessel as depicted.
You can make the same argument against the Tardis I think. Check with the Whovian experts.
I know Gay started as a powerful car and powerful computer programmed in Loglan and then got enhanced a few times. The biggest enhancement came from Ozma, but she was an intelligent machine first and foremost.
Jim
It reminded me of these wheeled trucks to move goods up&down stairs. Propably, it’s possible to use the tri-wheels to climb over higher obstacles.
Correct on both points. Gay Deceiver was originally built as a machine. All the add ons, and esp the Oz add ons, turned her into a sentient machine. The TARDIS is actually alive and sentient, as the New Series of Doctor Who has shown us and the original series may have at times hinted at. Voidships (Frank Herbert’s Pandora Sequence) are also sentient.
Yeah, but those are propelled by a human motor on feet, walking behind or ahead. If you’ve got these tri-wheels on a motor vehicle, where’s the drive axle? If it’s in the middle, then the whole arrangement would constantly be turning – which you wouldn’t want on a flat surface. And how could they be driven by three axles in a triangular arrangement? I see some mechanical problems there if the arrangement itself is (sometimes) going to rotate. Apparently the Landmaster actually exists and actually works, but I doubt it works at all like it would in the movie(s).
I think you could rotate the wheel assembly so that a damaged wheel could be replaced without stopping.
Handy when you have to fend off radioactive monsters while changing a flat. 
I vote for this yellow submarine that I once saw in some movie.
I think the Orbitals from Iain Banks’ Culture universe would work – they’re interstellar spacecraft, AND they’re the home of billions of sentients.
I also like the warships from the same series because of the names – nothing like a spacecraft capable of planet-busting named: “I Blame The Parents” or “Of Course I Still Love You.”
I’m also partial to some of the Mechs from Mechwarrior – sure, it gets hot sitting on top of a nuclear reactor after awhile, but a 70-ton fighting vehicle capable of moving at 60 kph and responding just like your body does while launching missiles and firing plasma cannons is sweet, and just the thing for rush hour.
But I guess the vehicle that first fired up my imagination was Tom Swift’s Flying Lab, which I read as a child – possibly before I was a toddler. A humongous jet with VTOL capabilities and a fully equipped science lab for mad science, and some pretty nifty if compact living quarters. The only reason you ever had to land was to fight evildoers. Sweet!
My Nominees–
Thunderbird Two Anderson always pleased & suprised with his designs. T-Bird 2 is obviously the most versitile vehicle in science fiction.
The Space: 1999 Eagle for offering originality of design, while sustaining with continuity with RL vehicles.
COMPARE WITH REAL APOLLO LEM
And then, there is the coolest of all…the place where the Vehicle & the Hero…OVERLAP!!!
More Than Meets The Eye, Baaaaaayyyyyybeee! 
The Hooded Swan from Brian Stableford’s Grainger novels. Second choice, the Tardis.
K.I.T.T.
He can even make Hasselhoff look cool.
And yet I pitched the book after a single reading (practically unheard of, for me) because there was no plot to speak of - nothing to compare with 20,000 Leagues or even the film of MotW (which obviously owed more to Robur, the Conqueror, a book I’ve never read).
Silver paint job? Dude, it was made out of *stainless steel!
*
And I’m morally obligated to mention Serenity as the coolest ship in any 'verse.
Does the TARDIS even really count as a “vehicle,” though? I was under the impression that it dematerialized at one point in the spacetime continuum and rematerialized in another predesignated point, *without traversing the intervening space. * So, technically it could be described as remaining stationary, since it doesn’t actually “move through” space-- it’s more akin to a teleportation device in this respect.
Okay, it’s a minor and probably indefensible point, but on the other hand, asking other vehicles to compete with TARDIS technology seems a bit like-- well, maybe not cheating exactly, but at the very least grossly unfair. I mean, the TARDIS’ ability to reconfigure itself internally and externally means that it could pretty much duplicate any other vehicle in existence. Although I suppose that doesn’t really count as far as the Doctor’s TARDIS is concerned, what with the dodgy chameleon cirucit and all… and its navigational ability has historically been famously unreliable as well.
Come to think of it, the series went out of its way on numerous occasions to point out just how laughably obsolete the Doctor’s TARDIS was compared to later models. Can it really be argued that the TARDIS is the apotheosis of coolness, if its own creators are on record as considering it woefully uncool?
Actually, now that I think of it, this same concern would also apply to the Millenium Falcon. It’s clear that pretty much everyone in the **Star Wars ** universe regards the Falcon as just about the most shamefully crappy-looking vehicle in existence, the sort of ship you’d be embarrassed to be seen standing too close to-- kind of the SW equivalent of an AMC Pacer with simulated wood-grain paneling.
My first pick is easily the TARDIS. It has a roomy interior and travels in space AND time almost instantaneously.
Second pick goes to just about any mech. Giant robots are too cool.
Third pick is a bit tougher, but I guess I’d have to say it goes to the Delorean (Back to the Future) largely because it flies and has Mr. Fusion. I love Mr. Fusion.