A bigger, heavier vehicle provides better crash protection than a smaller, lighter one, assuming no other differences between them. The part of the vehicle between the front bumper and the occupant compartment absorbs energy from crashes by crumpling. As a result, longer front ends offer better protection in frontal crashes. Heavier vehicles also tend to continue moving forward in crashes with lighter vehicles and other obstacles, so the people inside them are subject to less force.
Large vehicles aren’t as big a threat to people in small vehicles as they used to be. A lighter vehicle will always be at a disadvantage in a collision with a heavier vehicle. But in recent years automakers have reduced the threat that SUVs and pickups pose by lowering their energy-absorbing structures so that they line up with those in cars.
Fuel economy can be improved without sacrificing safety. Various technologies can raise fuel efficiency without reducing the vehicle’s weight. Research has also found that the heaviest vehicles can be made slightly lighter without compromising the safety they offer their occupants.