[Retric]

I think it's mostly weight, the newer one seems to be 300kg lighter which is a big deal. But that fact sheet was for the sedan so I don't know if it's apples to apples comparison. The worst modern model is 1.25 Studio (11/12-) 3d @ 16.4 seconds vs. 13 seconds from the 1975 model.

[ptaipale]

Newest cars are only lighter when compared to recent history. Cars of 1960's were much much lighter than today.

(big-family-sized Cortina DeLuxe of 1962 was 787 kg, present-day supermini Fiesta starts at 1041 kg).

[hx87]

The 1.25 Studio is so slow that it isn't available for sale in the USA--the cheapest $14k model here does 0-60mph in 9 seconds or so.