A lot of progress has been made here, for example, with airbag and belt systems, the design of the interior and in the entire body. What makes accidents so dangerous is the extreme force upon impact. Modern vehicles are designed so that these forces are systematically guided into the body. There are deformation zones there that reduce the energy. The impact on the driver and passengers is lower. The systems are constantly improved, for example with sensors and the trigger strategy of numerous built-in airbags, in the belt tightening systems or with active headrests.
But there is no perfect world here either. The engineers must make compromises because they cannot know with whom or what the vehicle will have an accident. The important thing is not protecting the vehicle, but rather the people. And naturally that also applies to contact with pedestrians and cyclists. For example, trendy SUVs are safer for the passengers in certain accident constellations, but their height and mass make them more dangerous than smaller and lighter cars for other parties involved in an accident. Despite good progress, SUVs remain problematic, for example in regard to protecting pedestrians, due to their size and geometry.