The Spymobile is a gadget-filled plumber truck that was once used by Mario and Luigi when they became Secret Agents. On the outside, it looks like an ordinary plumbers' truck. The Spymobile is a spoof to the Aston Martins that James Bond drives.
In The Super Mario Bros. Super Show! episode "On Her Majesty's Sewer Service", Secret Agent N presents the Spymobile to Mario and Luigi, stating that it packs more firepower than a battleship. However, Mario and Luigi do not get a demonstration of the Spymobile's capabilities until they drive it to pursue Koopfinger in Spy Land.
While Mario drives, the first feature that Luigi tests is the Plumber Scope, which serves as a built-in parascope. Using the plumberscope, Luigi is able to locate Koopfinger's limo.
In order to catch up with Koopfinger, Luigi activates the Plumber Pulsion, which are two shower heads that come out of the back of the Spymobile. By spraying water, the plumber pulsion makes the Spymobile move faster.
Koopfinger responds by having a Snifit shoot bullets at the Spymobile, though Luigi points out that the Spymobile's Plumber Windshield is made of Snifit-proof glass. Mario orders Luigi to fire the Plumber Missiles, which are actually two plungers, at the Snifit, knocking it out.
The Spymobile meets its match when Koopfinger orders an oversized Birdo to pick up the Spymobile, which it takes to his hideout. Although Mario and Luigi continue their adventure from that point, the Spymobile is never seen again.