From what I've ridden in the newer models it seems like internal cabin space remains the same or is genuinely getting smaller, but crumple zones keep increasing in size. There has to be some kind of ever increasing safety bar that keeps rising every year and this is the malicious compliance they're getting in response.
In 2100 every car will have a total of 1 person of internal space, span the size of a city block and will be made entirely of cotton balls to achieve a 4 star safety rating. For the 5 star rating you also have to make sure the driver is immortal so they can't die of old age.