Is a heavy SUV always safer than a light passenger car? Maybe not.

Recent research is challenging the long-standing belief that cars must be heavy to be safe. It turns out that the quality of the car may be just as important as the quantity of its bulk. Several studies show that design, safety features, and vehicle size (for crumple zones) can offset safety losses from reducing weight. And in addition to better fuel efficiency, lighter cars are also safer for other vehicles involved in an collision.

Carmakers have long argued that fuel economy standards compromise passenger safety because efficiency usually means lighter weights. And until recently government studies seemed to support the weight-safety tradeoff. But now it appears that other factors are as important as weight. There goes one more argument against improving vehicle fuel efficiency.