Not easy I would say.

Safety improvement means larger crumple zones, reinforcement, etc... Which mean a bigger and heavier vehicle if you want to keep the same capacity. That in turn means a more powerful engine, brakes, wheels and tyres, etc... further increasing the size and weight of the vehicle. This is an exponential factor.

Fuel economy and environmental stuff (which are linked) come with tighter engine control for better combustion and cleaner exhaust. It means tighter tolerances so simple tools may be less appropriate, and electronics.

And there are comfort elements that are hard to pass nowadays: A/C, power steering, door lock and windows. Mandatory safety equipment like airbags and ABS. Even simple cars like what Dacia makes are still bigger, heavier and more complex than older cars like the C15, they don't really have a choice.