I would expect the collision between lighter cars to be better for basic F=MA reasons.
It may be that collision between lighter cars is better. If so the reasons are not ‘basic F=MA reasons”. In the basic collision model neither m nor a change. The relevant mass is the mass of the persons body and the acceleration is determined by the collision speed and the degree to which the cars crumple. The mass of the (identical) cars is irrelevant (for ‘basic’ purposes).
Again, there may be more complex reasons why more mass in the cars makes them more dangerous. For example if shrapnel is considered a relevant factor and 0.5% of the mass of the car creates shrapnel then lower mass becomes desirable all else being equal. (Cars designed with modern engineering standards should in theory eliminate most reasons why lighter could be better, basically by bringing the reality closer to the basic model and reducing the extent to which ‘chaotic moving car parts’ cause injury on top of the ‘human stops suddenly’ problem.)
It may be that collision between lighter cars is better. If so the reasons are not ‘basic F=MA reasons”. In the basic collision model neither m nor a change. The relevant mass is the mass of the persons body and the acceleration is determined by the collision speed and the degree to which the cars crumple. The mass of the (identical) cars is irrelevant (for ‘basic’ purposes).
Again, there may be more complex reasons why more mass in the cars makes them more dangerous. For example if shrapnel is considered a relevant factor and 0.5% of the mass of the car creates shrapnel then lower mass becomes desirable all else being equal. (Cars designed with modern engineering standards should in theory eliminate most reasons why lighter could be better, basically by bringing the reality closer to the basic model and reducing the extent to which ‘chaotic moving car parts’ cause injury on top of the ‘human stops suddenly’ problem.)