Have mentioned it before.  Whatever the "new" eventually becomes it must include all of the modern "safety" bits ie: 
- side intrusion bars,
- pre determined front and rear crumple rates,
- survivable space and roll cage.
- more and more airbags
- pedestrian friendly front end, etc etc;
- stability control, and the latest,
- automatic braking control, and
- any "driver aid/protector that a regulator  or the "road safety industry" can think of in the meantime.
Of course as one adds the things mentioned above that means bigger springs, bigger brakes, more steel/strength, bigger (heavier) engine gear box etc. More "mass". 
All of that is "mass" and compensating "more mass";  and in many ways that is why the FJ toyo thing  and the Mini are the way they are, and not their 'retro' selves. 
Cheers 
RF
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