The Insurance Institute for Highway Safety toughened its standard for what makes a Top Safety Pick for 2010; the result is a much smaller list of qualifiers. While 94 model year 2009 vehicles qualified as IIHS Top Safety Picks, only 27 vehicles qualify this year.

That’s because the IIHS added a new rollover crash test that measures roof strength.

To get a good rating in the new test, a vehicle’s roof must withstand a force of four times the vehicle’s weight before reaching 5 inches of crush. That’s twice the required federal standard. To earn an acceptable rating, the roof must withstand a force 3.25 times the weight of the vehicle. The test involves a metal plate being pushed against one side of the roof at a constant speed.

“With the addition of our new roof strength evaluation, our crash test results now cover all four of the most common kinds of crashes,” said IIHS President Adrian Lund. “Consumers can use this list to zero in on the vehicles that are on the top rung for safety.”

To qualify for the award, a vehicle must be available with electronic stability control and earn the institute’s highest rating – good – in frontal offset, side, rear and the new rollover crash tests.

Lund said the new rollover test will spur changes: “Now that roof strength is a priority, we think manufacturers will move quickly to bolster roofs to do well in our roof strength test. This means consumers likely will have more Top Safety Pick choices for 2011.”

The new rollover standards cost several automakers spots on the list. Every Acura was on the list last year and none made the list this year. Toyota Motor Co., which includes Toyota, Lexus and Scion, had 11 winners last year and this year it has none. BMW, Mazda, Mitsubishi and Saab also failed to make the list after qualifying in recent years. The IIHS noted that the Ford Fusion and Honda Accord would have to make only minor changes to meet the required roof strength rating and the Toyota Camry could make the list with better head restraints.

The IIHS, a nonprofit organization funded by insurance companies, also supplied statistics backing the fact that automakers are rapidly adding safety equipment.

For the 2010 model year, 92 percent of passenger cars, 99 percent of SUVs and 66 percent of pickups have standard side airbags with head protection. More vehicles also have ESC. The system is now standard on 85 percent of passenger cars, 100 percent of SUVs and 62 percent of pickups.

Those numbers were lower last year and much lower just a few years ago.

The IIHS added the ESC requirement in 2007 based on research that showed ESC significantly reduces the risk of driver involvement in a crash. According to the IIHS, ESC lowers the risk of a fatal single-vehicle crash by about half and lowers the risk of a fatal rollover crash by as much as 80 percent.

Electronic stability control, also called antiskid control, is known by many names among auto manufacturers. General Motors’ system is called StabiliTrac, Ford’s is called AdvanceTrac and Chrysler dubs it the electronic stability program. Other names include vehicle dynamics control (Subaru), dynamic stability control (Volvo), vehicle stability assist (Honda) and vehicle stability control (Toyota).

No matter the name, electronic stability control uses sensors to detect a loss of grip or vehicle instability, then works automatically with the antilock braking system to apply individual brakes to help keep the vehicle on its intended path. In some cases, ESC also reduces engine power.

So how does that affect daily driving?

Hopefully, you’ll use ESC rarely, if ever.

However, if you approach a corner too fast and your vehicle begins to plow straight ahead, ESC detects that the vehicle is not on its intended path and tries to correct the situation by applying the inside brakes. This will rotate the vehicle through the turn and, hopefully, save you from going off the road.

Be aware that ESC can’t defy the laws of physics, so it won’t allow you to make a 90-degree left hander at 90 mph and it won’t really help on glare ice, but it can be quite helpful in emergency situations.

At right is the complete list of 2010 IIHS Top Safety Picks. Buyers looking for these vehicles, safety ratings for other vehicles and other automotive safety information, can turn to the IIHS’s Web site.