I'm all in on thinking modern cars are too fat but "maybe 600kg" is an absurd suggestion. That's less than a Smart Fortwo. There'll be a market for that but it's not what "Europeans want".
But most cars we had in the 80s were less than 1000kg, and that was fine.
Context differ from country to country, and from cities to countryside within countries, but in places where most of the population is concentrated in high-density cities, small cars or alternatives to cars are much, much more desirable than 2000+kg SUVs. Case in point, in France: more and more city centers just drastically reduce cars lanes and accessibility.
