AC Propulsion tzero
The tZero 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 1990s. It was the inspiration and direct predecessor of the Tesla line of electric cars. The only part of the tZero that was not proprietary was the body that was based on the Piontek Sportech sports car, yet many parts of the body and interior were extensively modified. It consists of a Kevlar & Carbon Fiber reinforced body built over a custom hand-built reinforced stainless steel fabricated to package batteries space frame with double wishbone independent suspension and rack and pinion steering. AC Propulsion utilized their AC-150 drivetrain, a single-speed electric system with an overall gear ratio of 9:1.
An experimental mule was made in the early 90s, and a complete vehicle was made the following year, launching in January 1996. Only 3 prototypes were built, the last one also being an official VIN production car. Prospect interested buyers included many big celebrities, well known scientists, and Silicon Valley engineers. Plans for a viable commercial production were eventually dropped in mid-2003. The name comes from t0, the mathematical symbol for a starting point in time. Due to high production costs, AC Propulsion ceased to produce the tZero. Only three were built, and as of 2025, only 2 survive. The only remaining examples are owned by the company itself and a private owner. The last tZero vehicle built used an advanced/updated ACP Gen 2 system that was capable of V2G. The tZero vehicles were extensively tested. Even including a cross country USA trip.
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, it eases the rear-wheel regenerative braking to prevent slides.
Original lead–acid battery powered tZero
The original version of the tZero roadster ran on 28 Johnson Controls Optima Yellow Top spiral wound AGM deep cycle lead–acid batteries in series, which produced 150 & 165 kW and 177 lbs·ft of torque at 336 volts and accelerated the car from a standstill to in 4.07 seconds. The single gear ratio limited the car's maximum speed to at 12,000 rpm, although it is said that early prototypes fitted with multiple gear ratios could hit. Even with the single ratio, lead–acid models are capable of completing a quarter mile drag race in 13.24 seconds. The expected range per charge of the tZero with the lead–acid batteries is as a result of consuming only 180 watt hours per mile on the highway and due to regenerative braking. The car could be charged from 0 to 95% within an hour. The initial base price of this version was to have been US$90,000. but later exceeded to $150KLithium-ion battery conversion
Tom Gage was contacted by Martin Eberhard about the tZero car which Gage had built, and was currently converting to lithium batteries, similar to those that make up the battery packs of laptop computers. Gage stated that Eberhard had multiple "schemes" and that he had to explain to Eberhard how unfeasible most of his concepts were. The conversion was done over six months from March through September, 2003 and gave the tZero a range. Lighter than the original version by, the lithium-ion conversion goes from in 3.6 seconds. The single gear ratio limits the car's maximum speed to just over at 13,000 rpm with proper gearing, though it has never been tested at greater than the electronic limit of. The base price of the car was US$220,000. Elon Musk and Martin Eberhard encouraged Tom Gage and Alan Cocconi to move the lithium-ion powered prototype into production. Eberhard then borrowed the converted tZero for three months and used it as a daily driver. The 2003 Li-ion tZero version achieved over 320 miles range per charge.JB Straubel then told Elon Musk about the newly converted, now lithium-ion powered tZero and arranged a test drive. Musk also encouraged AC Propulsion to commercialize the vehicle. Tom Gage, however, again deferred in favor of working on their electrified Scion xB called the eBox. But he put Elon Musk in contact with Martin Eberhard which led to Elon Musk's Series A funding of Tesla Motors in April, 2004 and their hiring JB Straubel.