HOW CAN BIG CARS CREATE ZERO EMISSIONS?

Generally, the more gasoline that is burned to power a vehicle, the more carbon dioxide is produced. Vehicles with larger engines, therefore, will tend to produce more CO2 emissions. According to the U.S. Environmental Protection Agency (EPA), one gallon of gasoline burned produces 20 pounds of CO2. Large cars with bigger engines tend to emit higher amounts of CO2.

Size has a big effect on a car's price, space, economy and styling. Large cars are roomier, better-styled and more expensive. Smaller cars are easier to park, easier on the wallet and less concerned with creature comforts.

Luxury and efficiency have often been strangers to each other in car design. Nevertheless, nowadays everything has and car companies are now producing big cars with small emissions. How can they achieve this?

The first and most important shift in the world of big cars has been to downsize engine capacity. Volvo Company was one of the first to adopt this approach with the 1.6-litre turbodiesel in the V70 and S80 in 2009. Other companies followed it quickly and 2.0-litre engines have been the best-sellers in many premium model ranges for the last 10 years.

Moreover, there were some major changes in technology for the internal combustion engine. Mazda has changed the automotive world with its high compression petrol engines and with lowering the combustion pressures of its diesels. This is a part of the Japanese firm’s ongoing Skyactiv program that has the potential to offer 30% improvements in economy and lower emissions. The technology consists of using spark-controlled compression ignition; it takes the best bits of petrol and diesel technology to burn fuel more in a quicker, more thorough fashion.

The materials being used for engine construction have also changed. Nowadays, Aluminum is the default choice for engines due to its lighter weight if compared with iron. Car makers are make engines with a broader spread of power that can be fine-tuned to suit the needs of the vehicle by refining the alloys used for different parts.

Change of gearboxes

Gearboxes have undergone a massive change for the last 20 years. Nowadays, we see the rise of the twin-clutch gearboxes offering quicker, more efficient changing. There has also been a return to the more traditional automatic gearbox but with more gears. That is why the eight-speed gearbox is perfectly normal now. More speeds allow the engine to work in its ideal operating state.

Moreover, the catalytic convertors have also improved. Today they last longer and treat the exhaust gases more effectively. There are also diesel particulate filters that operate at a greater rate. That is why the latest turbodiesel engines are now one of the cleanest combustion engines on the market.

Diesel technology has also included AdBlue treatment, which has been first used in the commercial vehicle world. By treating the exhaust gases with a urea-based solution, it significantly reduces the amount of harmful nitrous oxide (NOx) gas emitted.

Small diesels more toxic than big cars

Some independent tests have shown that small diesel cars pump out more toxic air pollutants than large engine cars. The results confound the popular assumption that bigger cars must be worse for the environment.

Recent models with an engine size below 1.5 liters emit approximately 9.3 times the legal limit of nitrogen oxides (NOx) in road tests by Emissions Analytics, which supplies independent data on the real-world emissions produced by cars.

 Cars with engines bigger than 2 liters emit on average 5.8 times the legal limit, which manufacturers are only required to meet in laboratory tests, despite admitting that those tests do not reflect how cars are driven on the road.