Hybrids, more formally called hybrid-electric vehicles or HEVs, are automobiles powered by both gasoline and electricity. In hybrids, the electricity supplements gasoline as a power source, leading to fewer emissions and better gas mileage. Despite their many benefits for the environment, hybrid cars do have some negative effects.
Hybrid cars have large batteries, much larger than the batteries in conventional automobiles, because the batteries help produce the electrical generation that makes the cars more fuel-efficient. These batteries typically are made of nickel or lithium, which are more environmentally friendly than the lead in traditional batteries but still have issues. Nickel is considered a probable carcinogen, according to hybridcars.com, and there are environmental concerns about nickel mining.
As of 2010, hybrid automobiles continue to cost considerably more than conventional vehicles. For instance, edmunds.com lists the price difference between the 2010 Ford Fusion hybrid and the conventional 2011 Ford Fusion at about $8,000. With the huge difference in price, it takes many years before the cars pay for themselves with savings on fuel costs. Hybrid cars also have more expensive parts, especially the batteries, and they generally don't hold their resale value as well as conventional vehicles.
Though hybrid cars are safe for drivers and passengers and perform as well in crash tests as conventional vehicles, they pose a couple of unique risks. Hybrid batteries operate at much higher voltages than those in conventional vehicles, raising the risk of electrocution, especially in an accident. Also, hybrid cars are extremely quiet, making them difficult for pedestrians to hear. A study cited by carsdirect.com that looked at the vehicles' risks to blind pedestrians determined that they are almost impossible to hear in urban areas when they are being operated in electric-only mode.