Editing Hybrid vehicle (section)

===Fluid power hybrid===
{{See also|Compressed-air car}}
[[File:2011 Chrysler Town & Country Touring - L -- 04-22-2011.jpg|thumb|right|Chrysler minivan, petro-hydraulic hybrid]]
[[File:Catvertroquette.jpg|thumb|right|French MDI petro-air hybrid car developed with Tata]]

[[Hydraulic hybrid]] and [[pneumatic hybrid vehicle]]s use an engine or regenerative braking (or both) to charge a pressure accumulator to drive the wheels via [[hydraulic]] (liquid) or [[pneumatic]] (compressed gas) drive units. In most cases the engine is detached from the drivetrain, serving solely to charge the energy accumulator. The transmission is seamless. Regenerative braking can be used to recover some of the supplied drive energy back into the accumulator.

====Petro-air hybrid====
A French company, [[Motor Development International|MDI]], has designed and has running models of a petro-air hybrid engine car. The system does not use air motors to drive the vehicle, being directly driven by a hybrid engine. The engine uses a mixture of compressed air and gasoline injected into the cylinders.<ref>{{cite web |url= http://www.aircars.tk/ |title=Learn everything about the compressed air cars! |website=Aircars.tk |access-date=2013-04-30 |archive-url=https://web.archive.org/web/20130520152900/http://aircars.tk/ |archive-date=2013-05-20 |url-status=dead }}</ref> A key aspect of the hybrid engine is the "active chamber", which is a compartment heating air via fuel doubling the energy output.<ref>{{cite web|url=http://www.thefuture.net.nz/mdi_tech.htm |title=MDI's active chamber |website=Thefuture.net.nz |access-date=2010-12-12 |url-status=dead |archive-url=https://web.archive.org/web/20110507151344/http://www.thefuture.net.nz/mdi_tech.htm |archive-date=2011-05-07 }}</ref> [[Tata Motors]] of India assessed the design phase towards full production for the Indian market and moved into "completing detailed development of the compressed air engine into specific vehicle and stationary applications".<ref>{{cite press release|url=http://www.tatamotors.com/media/press-releases.php?id=750 |title=MDI's air engine technology tested on Tata Motors vehicles |publisher=Tata Motors |date=2012-05-07 |access-date=2013-04-22 |url-status=dead |archive-url= https://web.archive.org/web/20130509064540/http://www.tatamotors.com/media/press-releases.php?id=750 |archive-date=2013-05-09 }}</ref><ref>{{cite web|url=http://www.gizmag.com/tata-motors-air-car-mdi/22447/ |title=Tata Motors enters second phase of air-car development |website=Gizmag.com |date=2013-05-07 |access-date=2013-04-22}}</ref>

====Petro-hydraulic hybrid====
{{Multiple image|direction=vertical|align=right|image1=Peugeot 2008 HYbrid air SAO 2014 0304.JPG|image2=Peugeot 2008 HYbrid air SAO 2014 0299.JPG|width=220|caption1=Peugeot 2008 HYbrid air/hydraulic concept car|caption2=Peugeot 2008 HYbrid air/hydraulic cutaway}}
Petro-hydraulic configurations have been common in trains and heavy vehicles for decades. The auto industry recently focused on this hybrid configuration as it now shows promise for introduction into smaller vehicles.

In petro-hydraulic hybrids, the [[energy recovery]] rate is high and therefore the system is more efficient than electric battery charged hybrids using the current electric battery technology, demonstrating a 60% to 70% increase in [[energy economy]] in US [[Environmental Protection Agency]] (EPA) testing.<ref>[http://www.epa.gov/otaq/technology/420f05006.htm EPA Announces Partnership to Demonstrate World's First Full Hydraulic Hybrid Urban Delivery Vehicle | Modeling, Testing, and Research | US EPA]. Epa.gov. Retrieved on 2012-04-18. {{webarchive |url=https://web.archive.org/web/20110809043402/http://www.epa.gov/otaq/technology/420f05006.htm |date=2011-08-09 }}</ref> The charging engine needs only to be sized for average usage with acceleration bursts using the stored energy in the hydraulic accumulator, which is charged when in low energy demanding vehicle operation. The charging engine runs at optimum speed and load for efficiency and longevity. Under tests undertaken by the US Environmental Protection Agency (EPA), a hydraulic hybrid [[Ford Expedition]] returned {{convert|32|mpgus}} City, and {{convert|22|mpgus}} highway.<ref name="demo-veh"/><ref name="Capturing the power of hydraulics"/> [[United Parcel Service|UPS]] currently has two trucks in service using this technology.<ref name="autoblog.com"/>

Although petro-hydraulic hybrid technology has been known for decades and used in trains as well as very large construction vehicles, the high costs of the equipment precluded the systems from lighter trucks and cars. In the modern sense, an experiment proved the viability of small petro-hydraulic hybrid road vehicles in 1978. A group of students at Minneapolis, Minnesota's Hennepin Vocational Technical Center, converted a [[VW Beetle|Volkswagen Beetle]] car to run as a petro-hydraulic hybrid using off-the-shelf components. A car rated at {{convert|32|mpgus|abbr=on}} was returning {{convert|75|mpgus|abbr=on}} with the 60&nbsp;hp engine replaced by a 16&nbsp;hp engine. The experimental car reached {{convert|70|mph|abbr=on}}.<ref name="Mother Earth News"/>

In the 1990s, a team of engineers working at EPA's National Vehicle and Fuel Emissions Laboratory succeeded in developing a revolutionary type of petro-hydraulic hybrid powertrain that would propel a typical American sedan car. The test car achieved over 80&nbsp;mpg on combined EPA city/highway driving cycles. Acceleration was 0-60&nbsp;mph in 8 seconds, using a 1.9&nbsp;L diesel engine. No lightweight materials were used. The EPA estimated that produced in high volumes the hydraulic components would add only $700 to the base cost of the vehicle.<ref name="demo-veh"/>

The petro-hydraulic hybrid system has a faster and more efficient charge/discharge cycling than petro-electric hybrids and is also cheaper to build. The accumulator vessel size dictates total energy storage capacity and may require more space than an electric battery set. Any vehicle space consumed by a larger size of accumulator vessel may be offset by the need for a smaller sized charging engine, in HP and physical size.

Research is underway in large corporations and small companies. The focus has now switched to smaller vehicles. The system components were expensive which precluded installation in smaller trucks and cars. A drawback was that the power driving motors were not efficient enough at part load. A British company ([[Artemis Intelligent Power]]) made a breakthrough introducing an electronically controlled hydraulic motor/pump, the Digital Displacement® motor/pump. The pump is highly efficient at all speed ranges and loads, giving feasibility to small applications of petro-hydraulic hybrids.<ref>{{cite web |url= http://artemisip.com/our-technology |title=Our Technology &#124; Artemis Intelligent Power |access-date=2013-10-17 |url-status=dead |archive-url= https://web.archive.org/web/20131017071459/http://www.artemisip.com/our-technology |archive-date=2013-10-17 }}</ref> The company converted a BMW car as a test bed to prove viability. The BMW 530i gave double the mpg in city driving compared to the standard car. This test was using the standard 3,000&nbsp;cc engine, with a smaller engine the figures would have been more impressive. The design of petro-hydraulic hybrids using well sized accumulators allows downsizing an engine to average power usage, not peak power usage. Peak power is provided by the energy stored in the accumulator. A smaller more efficient constant speed engine reduces weight and liberates space for a larger accumulator.<ref>{{cite web|url= http://www.artemisip.com/applications/on-road|title=On-road|access-date=2015-05-30|archive-url= https://web.archive.org/web/20150525063540/http://www.artemisip.com/applications/on-road|archive-date=2015-05-25|url-status=dead}}</ref>

Current vehicle bodies are designed around the mechanicals of existing engine/transmission setups. It is restrictive and far from ideal to install petro-hydraulic mechanicals into existing bodies not designed for hydraulic setups. One research project's goal is to create a blank paper design new car, to maximize the packaging of petro-hydraulic hybrid components in the vehicle. All bulky hydraulic components are integrated into the chassis of the car. One design has claimed to return 130 mpg in tests by using a large hydraulic accumulator which is also the structural chassis of the car. The small hydraulic driving motors are incorporated within the wheel hubs driving the wheels and reversing to claw-back kinetic braking energy. The hub motors eliminate the need for friction brakes, mechanical transmissions, driveshafts, and U-joints, reducing costs and weight. Hydrostatic drive with no friction brakes is used in industrial vehicles.<ref>{{cite web|url= http://www.mmh.com/article/lift_trucks_15_ways_the_lift_truck_is_evolving/D2/ |title=Lift Trucks: 15 ways the lift truck is evolving - Article from Modern Materials Handling |publisher=Modern Materials Handling |date=2011-08-01 |access-date=2013-04-22}}</ref> The aim is 170&nbsp;mpg in average driving conditions. The energy created by shock absorbers and kinetic braking energy that normally would be wasted assists in charging the accumulator. A small fossil-fuelled piston engine sized for average power use charges the accumulator. The accumulator is sized at running the car for 15 minutes when fully charged. The aim is a fully charged accumulator that will produce a 0-60&nbsp;mph acceleration speed of under 5 seconds using four wheel drive.<ref>{{cite web|url= http://inhabitat.com/hybrid-hydraulic-drive-vehicle-promises-170-mpg/ |first=Philip |last=Proefrock |title=Hybrid Hydraulic Drive Vehicle Promises 170 MPG |publisher=Inhabitat |date=2010-03-25 |access-date=2013-04-22}}</ref><ref>{{cite web|url= http://www.torquenews.com/1080/ingocar-valentin-tech-shatters-way-we-think-about-cars |first=Aaron |last=Turpen |title=INGOCAR from Valentin Tech shatters the way we think about cars |website=Torquenews.com |date=2012-02-15 |access-date=2013-04-22}}</ref><ref>{{cite web|url=http://www.valentintechnologies.com/default.asp |title=Welcome |website=Valentintechnologies.com |access-date=2013-04-22 |url-status=dead |archive-url= https://web.archive.org/web/20130421115904/http://www.valentintechnologies.com/default.asp |archive-date=2013-04-21 }}</ref>

In January 2011 industry giant Chrysler announced a partnership with the US Environmental Protection Agency (EPA) to design and develop an experimental petro-hydraulic hybrid powertrain suitable for use in large passenger cars. In 2012 an existing production minivan was adapted to the new hydraulic powertrain for assessment.<ref name="demo-veh"/><ref>{{cite web|url= http://www.gizmag.com/chrysler-announces-development-of-hydraulic-hybrid-technology-for-cars/17686/ |first=Mike |last=Hanlon |title=Chrysler announces development of hydraulic hybrid technology for cars |website=Gizmag.com |date=2011-01-26 |access-date=2013-04-22}}</ref><ref>{{cite press release|url= http://yosemite.epa.gov/opa/admpress.nsf/0/837c1d022dba18448525781d005995be?OpenDocument |title=EPA and Chrysler to Take Latest Hybrid Technology from Lab to Street/Partnership to adapt fuel efficient technology |website=Yosemite.epa.gov |date=2011-01-19 |access-date=2013-04-22}}</ref><ref>{{cite web|url= http://epa.gov/otaq/technology/research/research-hhvs.htm |title=Hydraulic Hybrid Research |publisher=US EPA |date=2010-10-18 |access-date=2013-04-22}}</ref>

[[PSA Peugeot Citroën]] exhibited an experimental "Hybrid Air" engine at the 2013 [[Geneva Motor Show]].<ref name=OG032313>{{cite news|title=Peugeot's Hybrid Air: the car of the future that runs on air|url= https://www.theguardian.com/environment/2013/mar/24/peugeot-hybrid-air-car-future |access-date=2013-03-25|newspaper=The Observer The Guardian|date=2013-03-23 |first=Tim |last=Lewis}}</ref><ref>{{cite web|url= http://inhabitat.com/peugeot-announces-plans-to-release-a-hybrid-car-that-runs-on-compressed-air-by-2016/ |title=Peugeot Announces Plans to Release a Hybrid Car That Runs on Compressed Air by 2016|author=Marc Carter|date=25 January 2013|access-date=2015-05-30}}</ref> The vehicle uses nitrogen gas compressed by energy harvested from braking or deceleration to power a hydraulic drive which supplements power from its conventional gasoline engine. The hydraulic and electronic components were supplied by [[Robert Bosch GmbH]]. Mileage was estimated to be about {{convert|118|mpgus|abbr=on|0}} on the Euro test cycle if installed in a [[Citroën C3]] type of body.<ref>{{cite web|url=http://blog.caranddriver.com/a-pair-of-peugeots-debuts-in-paris-one-prescient-and-possibly-good-for-118-mpg-one-practical/|title=A Pair of Peugeots Debuts in Paris: One Prescient (and Possibly Good for 118 mpg), One Practical|date=2014-10-02|access-date=2015-06-30|archive-date=2015-09-05|archive-url=https://web.archive.org/web/20150905072021/http://blog.caranddriver.com/a-pair-of-peugeots-debuts-in-paris-one-prescient-and-possibly-good-for-118-mpg-one-practical/|url-status=dead}}</ref><ref name=NYT030113>{{cite news|title=Compressing Gas for a Cheaper, Simpler Hybrid|url= https://www.nytimes.com/2013/03/03/automobiles/compressing-gas-for-a-cheaper-simpler-hybrid.html|access-date=2013-03-02|newspaper=The New York Times|date=2013-03-01|first=David |last=Jolly}}</ref> PSA Although the car was ready for production and was proven and feasible delivering the claimed results, Peugeot Citroën were unable to attract a major manufacturer to share the high development costs and are shelving the project until a partnership can be arranged.<ref>{{Cite web|url=https://www.autocar.co.uk/car-news/industry/psa-peugeot-citroen-seeks-partners-hybrid-air-tech|title=PSA puts Hybrid Air technology on back burner|website=Autocar}}</ref>