The Smart car is getting a lot of attention for its small size and style, and now it's earning impressive crash test ratings.

In recent Insurance Institute for Highway Safety tests, the 2008 Smart Fortwo, the smallest car for sale in the United States market, earned the top rating of good for front and side crash protection.

Its seat and head restraints earned the second highest rating of acceptable for protection against whiplash in rear impacts.

Smart Fortwo is classified a microcar, meaning it's smaller even than minicars. Weighing about 1,800 pounds, the Smart is more than 3 feet shorter and almost 700 pounds lighter than a Mini Cooper. It weighs about a third as much as one of the heaviest vehicles the Institute has tested, the BMW X5, a midsize SUV.

As the price of fuel climbs and tougher federal fuel economy requirements kick in, auto companies are expected to introduce more small vehicles to the market. The Smart is the smallest car the Institute ever has tested.

"The big question from consumers is, 'How safe is it?'", said IIHS president Adrian Lund. "All things being equal in safety, bigger and heavier is always better. But among the smallest cars, the engineers of the Smart did their homework and designed a high level of safety into a very small package."

The Institute's test results generally demonstrate how well vehicles stack up against others of similar size and weight. Frontal ratings can't be compared across weight classes, meaning a small car that earns a good rating isn't safer than a large car that's rated less than good.

"People base their buying decisions on a lot of factors," Lund said. "If you drive only in congested urban areas where speeds are low, a small car may be more practical than a big one. We conduct crash tests so people who want small cars can choose the ones that afford the best protection."

The Smart has a crashworthy design for its size and is equipped with the latest safety gear, which is especially important in a small car. This vehicle's standard equipment includes seat-mounted combination side airbags designed to protect both the heads and chests of the driver and passenger.

Also standard is electronic stability control, which helps drivers maintain control during emergency maneuvers or on slippery roads. It engages automatically when it senses vehicle instability, and Institute research has found that ESC lowers the risk of fatal single-vehicle crashes by about half.

While small cars are safer now than before, so are large cars. In every category of passenger vehicle (car, SUV, or pickup truck), the risk of death is higher in crashes of smaller, lighter models. For vehicles 1-3 years old during 2006, minicars experienced 106 driver deaths per million registered vehicles compared with 69 driver deaths in large cars.

People often choose very light cars for fuel economy, but small cars aren't necessary for to save fuel consumption.

"The Toyota Prius, for example, earns good front and side crash test ratings," Lund said. "It gets better fuel economy than a microcar, but it's bigger and weighs more so we would expect it would be more protective in serious crashes."