Westport Innovations Partners with Weichai Power, China's Largest Heavy Duty
Engine Manufacturer

Joint Venture Powers International Growth in Engine Development

VANCOUVER, BRITISH COLUMBIA--(Marketwire - July 16, 2008) - Westport
Innovations Inc. (TSX:WPT), a global leader in alternative fuel, low-
emissions transportation technologies, announced today that it has reached a
joint venture agreement with Weichai Power Co.,Ltd (HK:2338), China's largest
heavy duty engine manufacturer, and Hong Kong Peterson (CNG) Equipment
Limited. The new entity, Weichai Westport Inc. (WWI), will research, develop,
design, manufacture, market, distribute and sell advanced, alternative fuel
engines (and relevant parts and kits) for use in automobiles, heavy duty
trucks, power generation and shipping applications.

"We are working with the largest heavy duty engine manufacturer in China
where over 450,000 Heavy Duty trucks are introduced onto Chinese highways
every year," said David Demers, CEO at Westport Innovations. "Our High
Pressure Direct Injection (HPDI) LNG fuel system technology provides a clean,
low-emission solution to address a burgeoning market opportunity and the
pressing need in China and Asia to reduce high emissions in major cities.
With over 11% of the global heavy duty engine market share, Weichai is not
only a strong partner for the Chinese market, but a greater partner in global
expansion of low-emission, alternative fuel engines."

The rapid growth in China for energy, especially in the transport sector, is
creating a strong demand for newer, cleaner fuels in China such as natural
gas. China has a growing reserve of natural gas and is in various stages of
reviewing and approving a number of new LNG import terminals to be
constructed along its eastern shore. Transitioning natural gas from power
generation to transportation frees up increasingly expensive oil based fuels
for other applications and provides an economic advantage to the vehicle
owner where natural gas is less expensive than diesel on a per unit of energy
basis. According to The National Clean Vehicle Productivity Promotion in
China, there are over 185,000 Natural Gas Vehicles (NGV) in China and the
fueling infrastructure required to fuel these vehicles is growing quickly.

Adding to the scope of the joint venture, WWI will provide ancillary services
including inventory, warehousing, training, applications engineering, sales
promotion, technology consulting, installment, maintenance and after sale
service.

"As a leader in one of the world's largest heavy duty truck markets, this
partnership will help us expand into one of the fastest growing market
segments with innovative, clean technology," said Mr. Tan Xuguang, Chairman
and CEO of Weichai Power. "Our proven ability to develop, manufacture and
sell heavy duty engines combined with Westport's 'state of the art'
combustion technology will help launching a clean, low-emission heavy duty
LNG fueled engine in China in the shortest possible time."

Under the terms of the 30-year joint venture agreement, Westport's initial
investment is expected to be approximately US$4.5 million (30 million RMB)
equaling a 35 per cent share. Weichai Power and Hong Kong Peterson will hold
40 per cent and 25 per cent shares respectively. Westport Innovations and
Weichai Power will appoint two members each to the board of directors and
Hong Kong Peterson will appoint one. The Chairman of the board will rotate
between Weichai Power and Westport after each three-year term, with Weichai
power appointing the first board chair.

About Weichai Power

Weichai is the biggest powertrain manufacturer and owns the most integrated
heavy-duty vehicle value chain in China, including the manufacturing of the
engine, gearbox, axle, vehicle and other vehicle related parts. Weichai has
over 1,000 models of advanced diesel engine products, which are widely used
on heavy-duty trucks, large buses, construction machinery, marine vessels and
power generation. Weichai reports a 36% share of Chinese heavy-duty vehicle
market and more than 80% share of the over 5-ton construction machinery
market. Weichai is one of the top engine suppliers in the world with annual
sales of 300,000 engines. In particular, the WD series and WP Landking series
of heavy-duty, high-speed engines developed and manufactured by Weichai are
appreciated by consumers due to their high performance, reliability and
economic benefits. Weichai Power is a public company listed on the Hong Kong
Stock Exchange and Shenzhen Stock Exchange in China. Weichai has more than
2,000 authorized maintenance centers among China, which supplies convenient
and quick service for customers. Additional information can be found at
www.weichai.com.

About Westport Innovations Inc.

Westport Innovations Inc. is a leading global supplier of proprietary
solutions 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. Cummins Westport Inc., Westport's joint
venture with Cummins Inc., manufactures and sells the world's broadest range
of low-emissions alternative fuel engines for commercial transportation
applications such as trucks and buses. BTIC Westport Inc., Westport's joint
venture with Beijing Tianhai Industry Co. Ltd., manufactures and sells LNG
fuel tanks for vehicles.

Note: This document contains forward-looking statements about Westport's
business, operations, technology development or the environment in which it
operates, which are based on Westport's estimates, forecasts and projections.
These statements are not guarantees of future performance and involve risks
and uncertainties that are difficult to predict, or are beyond Westport's
control. Consequently, readers should not place any undue reliance on such
forward-looking statements. In addition, these forward-looking statements
relate to the date on which they are made. Westport disclaims any intention
or obligation to update or revise any forward-looking statements, whether as
a result of new information, future events or otherwise.

FOR FURTHER INFORMATION PLEASE CONTACT:

Westport Innovations Inc.
Darren Seed
Director, Investor Relations
(604) 718-2046
Email: invest@westport.com
Website: www.westport.com