The Elec-Taurus is a prototype electric car.
Homer once test drove an Elec-Taurus in order to get the free gift (it turns out to be Mel Gibson movie tickets). The drive reveals that the car can survive underwater, but electrocutes any lifeforms in the water with it. Homer quickly drops it off back at the dealership, broken and on fire. It is revealed that the car has a voice-chip, as it calls out in distress.
Behind the Laughter
The Elec-Taurus is a portmanteau of "electric" and "Taurus." The latter of those words is a reference to the Ford Taurus, once the best selling car in United States. In design and concept, however, it more resembles the General Motors EV1, an experimental electric car produced at about the same time as the episode "Beyond Blunderdome" (in which the Elec-Taurus made its only appearance).
Non canon appearances
The video games Road Rage and Hit & Run state that the Elec-Taurus is a prototype owned by Homer, and also by Lisa. In Hit & Run, The Elec-Taurus is the only car in the game that does not make engine noise, thanks to its electric motor. It is obtained after winning the Street Races of Level 1. In Road Rage, the Elec-Taurus is a convertible and Lisa's vehicle when playing as her.