NEW YORK (CNNMoney.com) - When the Insurance Institute for Highway Safety first started performing its own front crash tests in the mid-1990s, about half the vehicles scored "Marginal" or "Poor."

Today, cars perform so well on the frontal offset crash test that the Institute will no longer bother testing them on a routine basis.

Of the 106 current vehicle designs the Institute has tested, 88 earned the top rating of "Good." None are rated as "Poor," the worst of the four possible ratings. Only two, the Jeep Liberty SUV and Chevrolet Silverado pick-up, have "Marginal" ratings.

Now, instead of testing all new or redesigned models, the Institute will test only new versions of cars that have not previously earned a good rating or that have been so substantially changed that the new version is an entirely different vehicle.

"We've reached the point where we can declare victory and move on," said Institute president Adrian Lund in a March announcement of the procedure change.

But this improvement in front-crash effectiveness doesn't mean cars are as safe as they can be.

"This statement comes up about every 10 to 15 years, that we've done as much as we can," said Lund in an interview with CNNMoney.com. "But every decade we see improvements."

The key is to protect occupants in crashes that are less common but more dangerous. That's already what's happened with the emphasis on side impact crashes. With deaths in front crashes declining, side impact crashes account for an increasing percentage of motor vehicle fatalities.

Both NHTSA and the Insurance Institute rate vehicles for side impact protection. NHTSA is working on an additional side impact test as well. The new government test will involve an impact at an angle into a pole and will, essentially, require car manufacturers to install head-protecting side airbags in order to get passing scores.

"We're projecting this will save 1,000 to 1,300 lives a year," said NHTSA spokesman Rae Tyson.

Unlike the Insurance Institute's Lund, NHTSA sees less benefit from adding more impact protection. Future improvements with steel and airbags will lead to less significant safety gains.

Real improvements, he said, will come from computerized systems that can predict and prevent, or it least mitigate, accidents.

Systems like "electronic stability control," which is available under a variety of trademarked names from different manufacturers, are already having an effect in improved NHTSA rollover ratings for SUVs and trucks. Electronic stability control has also been shown to reduce single vehicle crashes in real-world driving.

Electronic crash avoidance and crash mitigation systems have the advantage that they can be added to vehicles without having to substantially reegineer them.

Other systems, already available in some high-priced luxury vehicles, automatically apply brakes to lessen an impending impact or close windows and sunroofs prior to an impact.

Anti-lock brakes have gotten more advanced, as well, taking into account that drivers often don't understand what the system does and, as a result, don't use the brakes as aggressively as possible in an emergency. Some cars now have systems that detect when a driver wants to stop quickly but is holding back, fearing a skid. The computerized system will apply the brakes fully, allowing the anti-lock braking system to prevent the wheels from skidding.

The challenge for NHTSA, said Tyson, will be to figure out how to assess the effectiveness of these sorts of systems. They rely on software and their programmers have to make decisions about how the system should behave.

A stability control system, for example, could be programmed to slow the car down as soon as there is any apparent danger of a skid.

Or it could be programmed to allow for a certain amount of "fishtailing" before kicking in and straightening the car out. Some of these systems even allow the driver to select how aggressively they will perform or even shut them off entirely.

Soon, NHTSA hopes to be able to provide consumers with a one-number rating system that will describe how safe a vehicle is including impact protection and crash avoidance.

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