The true car enthusiasts always tend to put themselves in a state of confusion. They might get awestruck by the incredible horsepower of a hybrid or get impressed by the endurance of a good old diesel car. The wide pool of cars available with alternative power-trains make things even more complicated. To wither away such doubts, fixing fuel economy as a parameter might be a good option.
Having a go at the diesel engine first, they boast of returning a better fuel economy, primarily due to its combustion process. Diesel engines make use of a piezoelectric injector that injects fuel at extremely high pressure that improves the fuel ignition. Needless to say, it propels the robustness and efficiency of engines to produce a cleaner combustion. The optimized efficiency allows drivers to keep a light weight on the gas pedal, which results in a more boosted fuel economy when compared to traditional gas-powered cars. The improved fuel economy culminates into an increased mileage on freeways. For example, the Audi A3’s 2.0-liter diesel engine records a gain of eight miles per gallon over its gas counterpart in the city but a 14-miles per gallon improvement, when tested on freeways. Also, frequent long drives avoid the clogging of the diesel particulate filter.
The diesel engines produce higher compression ratio (ratio of the volume of the combustion chamber from its largest capacity to its smallest capacity), they don’t need spark plugs to ignite the fuel. This saves you from the trouble of changing the spark plugs every 100,000 miles.
The improved fuel economy can also be associated with the fact that a gallon of diesel fuel contains more energy than a gallon of gasoline. Looking at it through the prism of eco-friendliness may tell you a different story. Diesel fuel has more carbon-density than its counterparts. When a gallon of diesel fuel is burnt, it produces 20% more emissions than for example, a gallon of gasoline is burnt. So, in no way will it (Diesel fuel) lessen the worries related to global warming.
Talking about the hybrids, they make use of the regenerative braking (It slows down the vehicle by converting its kinetic energy and storing it for later use, thereby charging the battery as the car slows down). This particular feature makes hybrids a favorite among the drivers who steer mostly in towns and are habitual with the stop and go form of driving. However, when it comes to cruising on freeways, the feature of regenerative braking in hybrids becomes redundant. Emphasizing on the facts, hybrid vehicles use about 40% less fuel in the city but only 20% less on freeways when compared with their counterparts. Pushing the point further, hybrids like Ford Fusion, Toyota Camry and Toyota Prius, are found to be more fuel-friendly in the cities than on freeways.
In most hybrids, a battery is the mainstay for the power-train. The lithium ion and nickel-hydrides batteries used in the hybrids, ages in no time. The aging depends on the number of charge discharge cycles a battery goes through. So, frequent long distance excursions can result in frequent replacements (A replacement can cost as much as $4,000.). This can prove to be a costly affair for the long-distance drivers for they might have to replace the battery every now and then. To the contrary, city-dwelling drivers who cover lesser miles and often deal with the bumper to bumper traffic, might spare themselves the extravagance.
When it comes to the eco-friendliness, the batteries used in hybrids may not be the greenest of option. The components of these batteries are extracted through the mining of nickel, copper and so-called rare earth metals. The production of lithium-ion batteries accounts for two to five percent of total hybrid emissions. Moreover, the nickel-hydride batteries emits the toxic sulfur oxide, roughly 22 pounds, which is quite high as compared to conventional vehicles (at 2.2 pounds). So, hybrids too have a fair share in the growing carbon emissions.
With the next generation of diesels and plug-in hybrids on the way, the above equation might change a bit. For the time being, diesel cars seem to be a safer option for your long drives.
Here is an infographic to understand the dilemma of a car buyer in a lucid fashion. Take a look!