Well F150s dropped a couple of hundred pounds go to aluminum. The Chevy Volt; I own the second generation; is three hundred pounds lighter.
Now if you go back twenty plus years or more before the age of crush points and advanced passenger safety systems both passive and active, yeah you can find your lighter weight cars. Cars which won't handle a head on with a car two sizes smaller.
Weight is one reason why manufacturers are loathe to commit all out for BEV, that thousand pounds of battery not only takes an hour to charge fully it weighs the same with or without a charge and imparts little range (sorry but if your range starts with a 1 or 2 its commuter range)
now take into account that many nameplates moved up in size classification. Accords certainly were not mid sized when they came out and even Chryslers minivan if not Honda's first weren't very big.
Efficiency gains are certainly there but much is lost with the way people drive.