The best driver assistance features on a new car are those that can't be shut off. Otherwise, they become little more than novelties that soon lose their safety impact, according to automotive experts.

One of the most appealing car tech features is forward collision warning, especially when combined with automatic braking. David Zuby, executive vice president and chief research officer at the Insurance Institute for Highway Safety, says extensive IIHS research shows forward collision warning reduces accidents by 7 to 10 percent.

Throw in automatic braking and the number jumps from 10 to 15 percent. One-fifth to one-half of owners with forward collision warning surveyed by the IIHS reported the system helped them avoid crashes.

Volvo auto braking

John Paul, senior manager of public affairs for AAA Northern New England, concurs on forward collision warning and adds cross-traffic alert as another feature worth its cost. He calls it a worthwhile driver's aid, especially for owners of smaller cars. The system incorporates radar sensors built into the rear bumper. It can sense traffic coming within 50 feet from both directions giving a driver time to stop. The aid is especially effective for drivers backing out between two taller vehicles.

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New car buyers should also consider getting the best lighting systems. Zuby says that includes high-intensity discharge (HID) headlamps, headlights that track around curves and automatic high beams. "Headlights and front crash prevention systems are the two technologies preventing crashes, and we would say are worth customers' money," Zuby says.

2015 Nissan Murano around view monitor
Backup camera and Around View Monitor in the 2015 Nissan Murano (U.S. News and World Report)

Another feature worth the money is a backup camera. These cameras are available as manufacturer-installed options or as aftermarket equipment. Wayne Cunningham, section editor of CNET's Car Tech channel, praises the feature for its aid in parking, especially in urban settings like his home base of San Francisco. The National Highway Traffic Safety Administration has mandated the cameras will become standard equipment by May 2018 for all vehicles under 10,000 pounds.

AAA's Paul adds a note of caution about backup cameras, which he favors in general. "As good as rearview cameras are, it doesn't take away the driver's responsibility to make sure the vehicle is clear before you back up. You can't let technology take the place of common sense."

Opinions are mixed on parking assistance aids among the three experts. Cunningham has found them useful in urban situations and would pay for them. "I would [pay] just to show off to my friends. It's like, ‘Hey, look, I'm not touching the wheel,'" he says of parallel park assist.

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Zuby adds, "For people who have trouble with parallel parking it works well." For people comfortable with parallel parking, the system takes longer than human guidance. Paul says the parking aids work best in spots that wouldn't require special skills.

Ford active park assist

Research and Markets, a company that offers market research products in the automotive sector, reports advanced driver assistance systems are broken into seven areas. They include tire pressure monitoring systems, park assistance systems, adaptive cruise control, blind spot detection, night vision systems, lane departure warning systems and other systems (including adaptive headlights, driver drowsiness monitoring, forward collision warning, a head-up display and driver monitoring systems).

Of that group, only tire pressure monitoring systems are currently mandated. That came in the wake of a massive recall in 2000 of Bridgestone tires on Ford vehicles because of under-inflation issues that led to them failing with tragic results. The Wall Street Journal at the time reported 46 deaths and 300 incidents were attributed to the tires. More than 6.5 million tires were recalled.

One technology not worth the additional cost is a lane departure warning system. It may be too good at its task, which irritates drivers sufficiently to shut the system down and never use it – in spite of paying a premium to have it installed.

For example, the refreshed 2016 Mitsubishi Outlander comes with available lane departure warning. When the vehicle starts to drift out of a lane without the turn signals being used, a chime goes off warning the inattentive driver.

When first introduced, lane departure warning was hailed as a driver assistance feature that could reduce accidents and save lives. But then it started to annoy drivers when it beeped. With the 2015 Outlander, drivers could switch it off but it would default to on when the vehicle was next started. For 2016, once lane departure is switched off, it stays off for good.

That makes it a driver assistance feature not worth the extra money. The consensus among experts interviewed is the best driver assistance features can't be mechanically defeated. "If you turn them off, they have no benefit," says Zuby, adding IIHS research hasn't found lane departure warning systems to be a significant factor in reducing crashes.

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Paul adds, "I think that happens to a lot of people with those systems. When it first came out, I thought [it was going to be the] next best thing to anti-lock brakes and [they're probably not] only because people do shut them off."

He says that's unfortunate because drowsy driving is a major problem in the United States. Paul says some reports claim 200,000 people fall asleep at the wheel daily. "If lane departure warning systems would wake those people up that would be good. In some cases the systems are so sensitive people shut them off," he adds.

Cunningham put in a plug for lane assist systems. Offered on vehicles from Mercedes-Benz and Hyundai, for example, these systems keep a vehicle between the lines. The systems use gentle steering compensation above a set speed to keep a car on track.

When it comes to safety, spend your money wisely and buy the features you plan to use. Budgets and safety features don’t have to be mutually exclusive.