NEW YORK (CNN/Money) - When you're choosing a new car, you've got to have priorities. You need performance. You need room to carry stuff. You need style. You need fuel economy. But there's one factor that should beat them all: safety.

It's a simple equation. Death or serious injury is too high a price to pay for spirited performance, good fuel economy or a low price tag. Fortunately, automotive technology has improved enough that, today, you should be able to find cars of almost any size, style and price that offer good levels of crash protection and avoidance.

While engineering improvements have made smaller vehicles safer, physics can't be cheated altogether. In a crash between a larger vehicle and a smaller one, you'll be better off in the larger one. In the case of an SUV, though, size carries the cost of higher ground clearance, which can cause poor handling and increases the risk of rollovers.

When shopping for a safe car, you have to look at the whole package. You want a car that will protect if you run into something straight on, if you get hit from the side and if you get hit from the back. You also want a vehicle that will keep you in control during emergency maneuvers.

Crash tests by the National Highway Traffic Safety Administration and the private Insurance Institute for Highway Safety are an important place to start. These are highly controlled tests, so results can be easily compared from one vehicle to another.

The IIHS does not test as many vehicles as NHTSA and IIHS does not test all available versions of each vehicle. For example, if a vehicle is available in two- and four-door versions, IIHS will test only the four-door version.

Results for four-door cars should not be considered to represent how a two-door version would perform, IIHS spokesman Russ Rader points out. Likewise, if a hard-top version of a car gets a "Good" rating from IIHS, that does not mean that a convertible version would have done as well.

Both the National Highway Traffic Safety Administration and the Insurance Institute for Highway Safety test cars for safety in frontal crashes.

NHTSA frontal crash test ratings Test: 35 mph into flat barrier Rating  Risk of serious injury  5 stars  10% or less  4 stars  11% to 20%  3 stars  21% to 35%  2 stars  36% to 45%  1 star  46% or greater   Source:  National Highway Traffic Safety Administration

Besides offering important information for consumers, the tests provide an incentive for manufacturers to improve safety performance.

In the last three years, for example, no vehicle has earned a "Poor" rating in IIHS's tests, a sign that carmakers have been working to improve those results. (You still need to check that ratings before buying, though. The Institute only tests cars that are totally new or substantially redesigned, so there are still brand new cars that have "Poor" ratings from IIHS.)

IIHS frontal crash test ratings Test: 40 mph into off-set barrier Letter rating  Meaning  G  Good  A  Acceptable  M  Marginal  P  Poor   Source:  Insurance Institute for Highway Safety

NHTSA and IIHS test vehicles -- and report results -- differently. NHTSA gives one- to five-star ratings that correspond to an occupants chance of serious injury in an accident. IIHS gives one of four letter grades ranging from "G" for Good to "P" for Poor. The Institute's Web site also provides details on exactly how the crash test dummies inside fared.

As front airbags have become standard equipment all passenger vehicles, more attention is being turned to the danger of side impacts.

NHTSA side impact crash test ratings Test:: 3,015 lb. barrier hitting at 38.5 mph Rating  Risk of injury  5 stars  5% or less  4 stars  6% to 10%  3 stars  11% to 20%  2 stars  21% to 25%  1 star  26% or greater   Source:  National Highway Traffic Safety Administration

When you're in a vehicle that gets hit from the side, there's little between you and the oncoming vehicle. That's why side airbags, particularly head-protecting side airbags, make such a big difference in side impact protection.

For side impacts, the IIHS test uses a raised impacting barrier that resembles the impact of a sport utility vehicle or pick-up into side of a vehicle. That type of crash represents a much graver risk of head injury, and therefore a greater risk of death, than the impact of a car.

IIHS side impact crash test ratings Test: Raised 3,100 lb. barrier moving at 31 mph. Smaller dummy used. Letter rating  Meaning  G  Good  A  Acceptable  M  Marginal  P  Poor   Source:  Insurance Institute for Highway Safety

The IIHS test is relatively new, so many new vehicles haven't been tested yet.

Currently, NHTSA's test mimics the impact of a car into side of the vehicle. The barrier used in NHTSA's test is lower, but it's also slightly faster-moving than the IIHS barrier.

Acceleration and handling aren't just for fun. The ability to get up to speed quickly and to turn without losing control can keep you from getting into a crash, and that's as safe as you could ever be. You don't need to buy a sports car to drive safely, but poor performance can present a hazard.

NHTSA rollover resistance ratings Star rating  Stability factor range  Chance of rollover  5  1.44 to 1.55  Less than 10 percent  4  1.18 to 1.44  10 to 20 percent  3  1.08 to 1.17  20 to 30 percent  2  1.02 to 1.07  30 to 40 percent  1  0.95 to 1.02  Greater than 50 percent   * Ranges are for vehicles that do not tip in dynamic test. Chances of rollover are for single-vehicle incidents.  Source:  National Highway Traffic Safety Administration

If you're shopping for an SUV, handling is a particularly important consideration. That's because a poor-handling SUV can go out of control and roll over in an accident.

By definition, an SUV is designed to go off-road. That means it needs a higher ground clearance which makes it more prone to tipping over. While rollovers are rare, they are quite a dangerous type of accident.

The NHTSA's rollover resistance rating gauges an SUV's propensity to tip over. It's a five-star rating system (the higher the better) but no SUV gets more than four stars and most get three stars.

If you're looking for an SUV, try to get one with a four-star rating. Only a few rate that high. Of course, since rollovers are rare, you don't want to skimp on safety in other areas.

If you are considering an SUV with a 3-star rating, look at the vehicle's Static Stability Factor. That number, which will be between 1.0 and 1.5, should be as high as possible. As a general rule, you should not consider an SUV with a SSF of less than 1.15.

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NHTSA also does what it calls a dynamic stability test. The vehicle is put through a series of turns at speeds from 35 to 50 miles per hour. Tipping counts as a failure. If a vehicle passes the test, it is given an extra half star, which may move it up to a higher star rating.

So far, no SUVs with a static stability factor higher than 1.15 have failed the dynamic stability test. For more on NHTSA's rollover ratings, see How safe is your SUV.