Cummins Westport ISL G In Use Test Results Beat 2010 Emissions Regulations

published: May 4, 2009

VANCOUVER, BC– Cummins Westport Inc. (CWI), a leading provider of high-performance, alternative fuel engines for the global market, announced today that an ISL G in-use emissions test performed on an urban transit bus recorded emissions significantly lower than the 2010 EPA and California Air Resources Board (CARB) Heavy Duty emission regulations.

“The ISL G continues to demonstrate low emission and performance benefits as field results are obtained,” said Gordon Exel, Vice President and GM -Americasat Cummins Westport. “ISL G emissions below 2010 emission regulations in both the laboratory and on the road with simple, maintenance free three way catalyst aftertreatment is an important benefit for our customers.”

The Cummins Westport (CWI) 8.9 litre ISL G natural gas engine features new combustion technology (Stoichiometric Cooled EGR) that enabled the ISL G to be the first heavy duty engine to meet the 2010 EPA emissions regulations.

To test the ISL G not only in the laboratory, but more importantly out in the real world under real-world vehicle operating conditions, Cummins Westport with the support of Sacramento Regional Transit District commissioned Sensors Inc, a global leader for Portable Emissions Measurement Systems (PEMS), to perform an in-use tailpipe emissions test in accordance with EPA’s Heavy Duty In-Use Testing guidelines.

The test was conducted on a 2008 40 foot Orion VII Low Floor natural gas bus powered by an ISL G 280, driven by a Sacramento Regional Transit bus driver on city and highway routes. The U.S. EPA in-use testing procedures were designed such that the heavy-duty engine emissions are controlled over the full range of speed and load combinations commonly experienced in vehicle applications.

Sensors Inc concluded that emissions were significantly lower than the 2010 EPA Heavy Duty in use emission requirements.

About Cummins Westport Inc.

Cummins Westport Inc. designs, engineers and markets spark-ignited natural gas engines for medium- and heavy-duty transportation applications such as trucks and buses. Cummins Westport is a joint venture of Cummins Inc. (NYSE: CMI), a corporation of complementary business units that design, manufacture, distribute and service engines and related technologies, including fuel systems, controls, air handling, filtration, emission solutions and electrical power generation systems, and Westport Innovations Inc. (NASDAQ: WPRT/TSX: WPT), a global leader in alternative fuel, low-emissions technologies that allow engines to operate on clean-burning fuels such as compressed natural gas (CNG), liquefied natural gas (LNG), hydrogen and biofuels such as landfill gas. :: www.cumminswestport.com

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This document contains forward-looking statements, including statements regarding the demand for our products, the future success of our business and technology strategies, investment, cash and capital requirements, intentions of partners and potential customers, the performance and competitiveness of our products and expansion of product coverage, future market opportunities, speed of adoption of natural gas for transportation, growth in demand as a result of new emission standards and terms of future agreements. These statements are neither promises nor guarantees, but involve known and unknown risks and uncertainties and are based on assumptions that may cause our actual results, levels of activity, performance or achievements to be materially different from any future results, levels of activities, performance or achievements expressed in or implied by these forward looking statements. These risks and assumptions include risks and assumptions related to our revenue growth, operating results, industry and products, the general economy, conditions of and access to the capital and debt markets, governmental policies and regulation, technology innovations, fluctuations in foreign exchange rates, global government stimulus packages, the acceptance of natural gas vehicles in fleet markets, the relaxation or waiver of fuel emission standards, the inability of fleets to access capital or government funding to purchase natural gas vehicles, the sufficiency of bio methane for use in our vehicles, the development of competing technologies as well as other risk factors and assumptions that may affect our actual results, performance or achievements or financial position discussed in our most recent Annual Information Form and other filings with securities regulators. Readers should not place undue reliance on any such forward-looking statements, which speak only as of the date they were made. We disclaim any obligation to publicly update or revise such statements to reflect any change in our expectations or in events, conditions or circumstances on which any such statements may be based, or that may affect the likelihood that actual results will differ from those set forth in the forward looking statements except as required by National Instrument 51-102.

More Information

Cummins Inc.

Jon Mills

External Communications

T 317-658-4540

jon.mills@cummins.com

www.cummins.com

Cummins Westport Inc.

Darren Seed

Vice President, Investor Relations and Communications

T 604-718-2046

invest@westport.com

www.cumminswestport.com