Exhaust gas gas is undesirable, noxious, or toxic substances, such as carbon monoxide (CO) from incomplete combustion, hydrocarbons (properly indicated as CH, but typically shown simply as "HC" on emissions-test slips) from unburnt fuel, nitrogen oxides (NO) from excessive combustion temperatures, and particulate matter (mostly soot). Exhaust gas temperature (EGT) is important to the functioning of the catalytic converter of an internal combustion engine. It may be measured by an exhaust gas temperature gauge. EGT is also a measure of engine health in gas-turbine engines (see below). During the first two minutes after starting the engine of a car that has not
Electric bus and unpleasant exhaust fumes. However, improvements were made to the gasoline-powered car that caused the electric car to lose some momentum. The hand crank was soon replaced with an electric starter and gasoline-powered vehicles became more affordable. Gasoline cars soon overcame the popularity of electric powered vehicles. By 1935, electric cars practically disappeared. It was not until the 1970s when a gas shortage hit, causing gas prices to soar, that electric cars entered back into the marketplace. Gasoline-powered cars still remained more popular due to better performance and reliability. The 1990s saw electric cars made more popular as societal concern