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{{Infobox electric vehicle
| name = t<sub>zero</sub>
| image = Tzero - The first Tesla vehicle.jpg
| caption = The AC Propulsion tZero with the top off
| manufacturer = [[AC Propulsion]]
| aka = 
| production = 
| model_years = 
| assembly = 
| designer = 
| class = Sports car
| body_style = 2 passenger coupe
| layout = Rear mid-engine, rear-wheel drive
| platform = AC Propulsion AC150
| related = {{Unbulleted list|[[Lotus Elise]]|[[Tesla Roadster (2008)]]|Piontek Sportech}}
| motor = 
| battery = 
| electric_range = 
| charging = 
| transmission = 
| propulsion = 
| wheelbase = {{convert|NNN|in|mm|0|abbr=on|order=flip}}
| length = {{convert|NNN|in|mm|0|abbr=on|order=flip}}
| width = {{convert|NNN|in|mm|0|abbr=on|order=flip}}
| height = {{convert|NNN|in|mm|0|abbr=on|order=flip}}
| weight = {{convert|NNN|-|NNNN|lb|kg|0|abbr=on|order=flip}}
| predecessor = 
| successor = 
| sp = us
}}
[[File:Wally Rippel with tzero.jpg|thumb|[[Wally Rippel]] showing his tZero prototype at [[Caltech]] in 2024]]

The '''tZero''' (a mathematical symbol meaning, 'time from a standing start in sequence') is a hand-built [[battery electric vehicle|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, Inc.|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 suspension|double wishbone independent suspension]] and rack and pinion steering. AC Propulsion utilized their [[AC Propulsion#Vehicles using an AC Propulsion electric drivetrain|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 [[Tzero|''t''<sub>0</sub>]], the [[mathematical symbol]] for a starting point in time.<ref>{{cite web |url=http://www.acpropulsion.com/products-tzero.html |title=AC Propulsion &#124; Creating electric vehicles that people want to drive |accessdate=2014-06-10 |url-status = dead|archiveurl=https://web.archive.org/web/20140714144332/http://www.acpropulsion.com/products-tzero.html |archivedate=2014-07-14 }}</ref> Due to high production costs, AC Propulsion ceased to produce the tZero.{{when|date=February 2020}} Only three were built, and as of 2025, only 2 survive.<ref name=Electrek-2017-05-11>{{cite news |url= https://electrek.co/2017/05/11/tesla-roadster-tzero-electric-car-lost-fire/ |title= A piece of electric car history up in flames: several Tesla Roadsters and original Tzero lost in devastating fire |author= Fred Lambert |authorlink=Fred Lambert |date= 11 May 2017 |work= [[Electrek]] }}</ref> 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 (vehicle-to-grid & vehicle-to-vehicle charging system). The tZero vehicles were extensively tested. Even including a cross country USA trip. {{citation needed|date=February 2020}}

Adjustable Regenerative Braking: Because the car recharges its batteries when the [[throttle]] is released{{snd}} slowing sharply as energy is recaptured{{snd}} 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&nbsp;m/s²), it eases the rear-wheel [[regenerative braking]] to prevent slides.

==Original lead–acid battery powered tZero==
[[Image:Acp tzero dsc00309.jpg|thumb|200px|right|Original [[lead–acid battery|lead–acid]] [[battery pack]] ]]
The original version of the tZero roadster ran{{when|date=February 2020}} on 28 [[Johnson Controls]] Optima Yellow Top spiral wound AGM deep cycle [[lead–acid battery|lead–acid batteries]] in [[Series and parallel circuits#Series circuits|series]], which produced 150 & 165&nbsp;[[Watt#Kilowatt|kW]] (220 horsepower) and 177&nbsp;lbs·ft (240&nbsp;N·m) of [[torque]] at 336&nbsp;[[volt]]s and accelerated the {{convert|1040|kg|lb|abbr=on}} car from a standstill to {{convert|60|mph|abbr=on}} in 4.07 seconds. The single gear ratio limited the car's maximum speed to {{convert|90|mph|abbr=on}} at 12,000&nbsp;rpm, although it is said that early prototypes fitted with multiple gear ratios could hit {{convert|170|mph|km/h}}. Even with the single ratio, lead–acid models are capable of completing a quarter mile (400&nbsp;m) drag race in 13.24 seconds. The expected range per charge of the tZero with the lead–acid batteries is {{convert|90|to|120|mi|abbr=on}} as a result of consuming only 180 watt hours (DC) per mile (112 [[Watt-hour|Wh]]/[[Kilometre|km]]) 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 $150K {{citation needed|date=February 2020}}

==Lithium-ion battery conversion==
[[Image:Acp tzero LH wo cover.JPG|thumb|200px|New [[lithium-ion battery]] pack]]
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 pack]]s 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.<ref name="ChargedEV">{{cite web|last1=Morris|first1=Charles|title=Tom Gage on ZEV mandates, Tesla's early days, BMW's EV commitment and V2G tech|url=http://chargedevs.com/features/tom-gage-on-zev-mandates-teslas-early-days-bmws-ev-commitment-and-v2g-tech/|publisher=Charged Electric Vehicles Magazine|date=2014-04-07|quote=Gage: I had a neighbor named Steve Casner, who had a Toyota RAV4 electric, and I always had an EV in my front yard, so we got to talking. He was working at a company with Martin Eberhard, so he told Martin about me. Martin called me, and he had all these schemes, and I was sort of talking through what the realities were. We were just converting the tZero over to lithium-ion batteries. He got involved with that. He actually put some investor money – a small amount – into AC Propulsion, and we finished the conversion of the tZero to lithium-ion batteries.}}</ref><ref name="Quiet Thunder">{{cite web|last1=Shnayerson|first1=Michael|title=Quiet Thunder|url=http://www.vanityfair.com/politics/features/2007/05/tesla200705?printable=true&currentPage=all|publisher=CondéNet <!--  archiveurl=http://web.archive.org/web/20071013195347/http://vanityfair.com/politics/features/2007/05/tesla200705|archivedate=2001-05-14| --> |date=2007-05-14|quote="Musk isn't the one who had the Eureka! moment. That was […] Martin Eberhard. Like anyone else in 2003, the then 43-year-old Eberhard knew that billion-dollar markets had grown almost overnight for laptop computers and cell phones. Rivals were spending huge sums on R&D to pack ever more energy into the lithium-ion batteries that powered those devices. One day Eberhard had a simple thought: Why not put lithium-ion cells into cars? […] Eberhard commissioned a shy, gifted, sometimes difficult California pioneer of electric vehicles named Alan Cocconi to put a pack of lithium-ion batteries into Cocconi's latest electric-vehicle kit car, the T Zero."}}</ref> The conversion was done over six months from March through September, 2003 and gave the tZero a {{convert|300|mi|km|adj=on}} range.<ref name="ACP tZero press">{{cite web|last1=Chow|first1=Yee|title=AC Propulsion Debuts tzero with LiIon|url=http://www.acpropulsion.com/pressreleases/09.15.2003%20tZero%20Debut.pdf|publisher=AC Propulsion|location=San Dimas, CA|date=2003-09-15|access-date=2014-11-06|archive-url=https://web.archive.org/web/20160304023131/http://www.acpropulsion.com/pressreleases/09.15.2003%20tZero%20Debut.pdf|archive-date=2016-03-04|url-status = dead}}</ref> Lighter than the original version by {{convert|500|lb|kg|abbr=on}}, the lithium-ion conversion goes from {{convert|0|-|60|mph|abbr=on}} in 3.6 seconds. The single gear ratio limits the car's maximum speed to just over {{convert|140|mph|abbr=on}} at 13,000 rpm with proper gearing, though it has never been tested at greater than the electronic limit of {{convert|105|mph|abbr=on}}. 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.<ref name="ChargedEV"/><ref name="SFGate">{{cite news|last1=Taylor|first1=Michael|title=Hot sports car with no gas tank / Electric roadster's maker says it does 130 mph -- but it doesn't come cheap|url=http://www.sfgate.com/news/article/Hot-sports-car-with-no-gas-tank-Electric-2514556.php|publisher=S.F. Chronicle|date=2006-08-09|quote=Eventually, he got in touch with Tom Gage, president of AC Propulsion, a San Dimas (Los Angeles County) firm that had already made the tZero, a brutally fast electric-powered sports car. AC had made only a few cars, and Eberhard says he invested in the company and drove its lithium ion-battery-powered car for about three months "as a daily driver."}}</ref> 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.<ref name="Quiet Thunder" /> Tom Gage, however, again deferred in favor of working on their electrified [[Scion xB]] called the [[AC Propulsion eBox|eBox]]. But he put Elon Musk in contact with Martin Eberhard<ref>{{cite magazine|last1=Siry|first1=Daryl|title=Will the Real Tesla Founder Please Stand Up?|magazine=Wired|url=https://www.wired.com/2009/06/tesla-founder/|publisher=Condé Nast|date=2009-06-25|quote=...it is interesting to note that neither Martin Eberhard or Elon Musk came up with the idea of an electric sportscar with excellent range and amazing acceleration. As is evident in some of the emails Elon presents on his blog, the credit rests with a company few outside EV circles has heard of. {{br}} AC Propulsion developed the idea [using lead–acid batteries originally], and both Eberhard and Musk initially approached the San Dimas, California, company to build the car. Tom Gage and Alan Cocconi had built the tZero, which is essentially the prototypical Tesla Roadster with a 0–60 time of 3.6 seconds and a range of more than 200 miles using [the upgraded] commodity lithium-ion cells. {{br}} One way to look at this is the real technology visionaries were the folks at AC Propulsion, but they lacked the entrepreneurial vision to see just how big an idea it could become and the means to achieve it. Both Eberhard and Musk saw the importance{{snd}} and potential{{snd}} of what Gage and Cocconi had created. When Eberhard and Musk approached them individually to prod them into taking the next step and produce the vehicle, Gage opted instead to introduce Musk to Eberhard and get back to work creating the eBox, an electrified Scion xB that Gage considered more practical and economical.}}</ref> which led to Elon Musk's Series A funding of Tesla Motors in April, 2004 and their hiring JB Straubel.<ref name="SFGate"/>

==Long Ranger genset trailer==
[[Image:Acp tzero DSC00467.jpg|thumb|200px|ACP backtracking genset trailer]]
AC Propulsion also built a [[range extender]] for the tZero. Known as the '''Long Ranger''', it was a portable [[Internal combustion engine|internal combustion]] powered generator mounted on a trailer that could be towed behind the car and feed power to the batteries during travel. A tZero with Long Ranger was a [[series hybrid]]. The trailer used a {{Val|500|ul=cc}} [[Kawasaki Heavy Industries Motorcycle & Engine|Kawasaki]] engine with a {{Convert|9.5|gal|L}} fuel tank and achieved {{convert|30|mpgus|L/100 km|abbr=on}} in highway driving over at least {{convert|20000|miles|abbr=on}}. It was rated at {{convert|20|kW|hp|abbr=on}} DC output and could maintain {{convert|60|-|80|mph|abbr=on}}.{{Citation needed|date=September 2024}} The trailer incorporated a novel "backtracking" feature that automatically steered the trailer wheels allowing even novice drivers to easily back a trailer through complex maneuvers; the company published a video demonstrating the ease with which the trailer could be backed through a set of slalom cones.{{Citation needed|date=September 2024}}

==Production==
{{As of|August 2023}}, only 2 of the 3 tZero production models remain, since Gruber Motor Company's car was destroyed in a building fire in May 2017.<ref name=Electrek-2017-05-11/> The surviving two models are displayed at the [[Petersen Automotive Museum]].<ref>{{Citation |last=Banner |first=Justin |title=Tesla at the Petersen Auto Museum: A History of the American Icon |orig-date=17 November 2022 |url=https://www.motortrend.com/news/petersen-auto-museum-elon-musk-tesla-exhibit/ }}</ref>

==See also==
* [[La Jamais Contente]]
* [[Keio University Eliica]]
* [[Lightning GT]]
* [[Think Global AS]]
* [[Venturi Fétish]]
* [[Wrightspeed X1]]
* [[Aptera Motors]]
* [[Tesla Roadster (disambiguation)|Tesla Roadster]]

==References==
{{reflist}}

==External links==
{{Commons category}}
* [https://query.nytimes.com/gst/fullpage.html?sec=travel&res=9B01E3DC123AF93AA2575AC0A9659C8B63 Lots of Zoom, With Batteries] ''The New York Times'', September 19, 2003

[[Category:Automotive technologies|Tzero]]
[[Category:Electric sports cars]]
[[Category:Electric concept cars]]
[[Category:Production electric cars]]
[[Category:AC Propulsion vehicles]]