The tZero (a mathematical symbol meaning, 'time from a standing start in sequence') is a hand-built electric sports car designed and built in very limited numbers by the U.S. pioneering company AC Propulsion in the mid 1990's.

Experimental mule in early 90's, a complete vehicle the following year and launched in January 1996, only 3 prototypes were built, the last one also being an official VIN production car.

[citation needed] Adjustable Regenerative Braking: Because the car recharges its batteries when the throttle is released – slowing sharply as energy is recaptured – It can be driven hard using only the accelerator pedal.

Also, if the car detects a turn with more than half a g-force (5 m/s²), it eases the rear-wheel regenerative braking to prevent slides.

on 28 Johnson Controls Optima Yellow Top spiral wound AGM deep cycle lead–acid batteries in series, which produced 150 & 165 kW (220 horsepower) and 177 lbs·ft (240 N·m) of torque at 336 volts and accelerated the 1,040 kg (2,290 lb) car from a standstill to 60 mph (97 km/h) in 4.07 seconds.

The expected range per charge of the tzero with the lead–acid batteries is 90 to 120 mi (140 to 190 km) as a result of consuming only 180 watt hours (DC) per mile (112 Wh/km) on the highway and due to regenerative braking.

Elon Musk and Martin Eberhard encouraged Tom Gage and Alan Cocconi to move the lithium-ion powered prototype into production.

JB Straubel then told Elon Musk about the newly converted, now lithium-ion powered tZero and arranged a test drive.

[citation needed] As of August 2023[update], only 2 of the 3 tzero production models remain, since Gruber Motor Company's car was destroyed in a building fire in May 2017.