Portland is a city located in the Northwestern United States, near the confluence of the Willamette and Columbia rivers in the state of Oregon. It has an estimated population of 568,380, and has been referred to as the greenest city in the United States.[6] Portland is Oregon's most populous city, and the third most populous city in the Pacific Northwest, after Vancouver, British Columbia, and Seattle, Washington. Approximately two million people live in the Portland metropolitan area, the 23rd most populous in the United States as of July 2006. Portland was incorporated in 1851 and is the county seat of Multnomah County.[8] The city extends slightly into Washington County to the west and Clackamas County to the south. It is governed by a commission-based government headed by a mayor and four other commissioners. The city and region are noted for strong land-use planning and investment in public transit, supported by Metro, a distinctive regional-government scheme. Portland is also known for its large number of microbreweries and microdistilleries, and as the home of the Trail Blazers NBA basketball team. Portland lies in the Marine west coast climate region, marked by warm summers and rainy but temperate winters. This climate is ideal for growing roses, and for more than a century, Portland has been known as "The City of Roses" with many rose gardens—most prominently the International Rose Test Garden.

Gasoline Engines

Gasoline engines have the advantage over diesel in being lighter and able to work at higher rotational speeds and they are the usual choice for fitting in high-performance sports cars. Continuous development of gasoline engines for over a hundred years has produced improvements in efficiency and reduced pollution. The carburetor was used on nearly all road car engines until the 1980s but it was long realized better control of the fuel/air mixture could be achieved with fuel injection. Indirect fuel injection was first used in aircraft engines from 1909, in racing car engines from the 1930s, and road cars from the late 1950s.

Gasoline Direct Injection (GDI) is now starting to appear in production vehicles such as the 2007 BMW MINI. Exhaust gases are also cleaned up by fitting a catalytic converter into the exhaust system. Clean air legislation in many of the car industries most important markets has made both catalysts and fuel injection virtually universal fittings. Most modern gasoline engines are also capable of running with up to 15% ethanol mixed into the gasoline - older vehicles may have seals and hoses that can be harmed by ethanol. With a small amount of redesign, gasoline-powered vehicles can run on ethanol concentrations as high as 85%. 100% ethanol is used in some parts of the world (such as Brazil), but vehicles must be started on pure gasoline and switched over to ethanol once the engine is running. Most gasoline engines cars can also run on LPG with the addition of an LPG tank for fuel storage and carburetion modifications to add an LPG mixer. LPG produces fewer toxic emissions and is a popular fuel for fork lift trucks that have to operate inside buildings.