This Phrase is a combination of the well renouned word "wank" which means to jerk, as in jerk off. An chariot as in a most prestigious form of transport/recreation, like a bed or public transport. With linking these two words you can come to the conclusion that wank chariot is a place where you can go an feel like a king an more powerfull whilst you enjoy a fine masturbation marathon.
"Sorry guys I can't come out for a drink to tonight, I am going to my wank chariot for a quick couple then going for an early nights sleep"
"there is nothing like going home to your own wank chariot"