I guess everybody here agrees to that fact that safety is not just dependent on the weight of the cars. (Though I myself quoted EuroNCAP's safety ratings for volkswagen and ford
). But if we have to compare two cars of same generation and same category, obviously there is no point comparing vehicles from two different generations, I would still prefer a heavier car. Traditionally the makers of heavier cars have had higher percentage of safer cars too volkswagen, ford, volvo. Traditionally they have also been cars with better handling. I believe that lighter cars can get unsettled on rough roads at high speeds.
Regarding formula-1 cars being light and safe, we have to account for the fact that they are made of carbon fiber bodies and are also aerodynamically highly efficient. Not many road cars are. Formula1 cars do get unsettled upon hitting a kerb.
Having said all that have to agree that things cannot be generalized. Until our government comes out with crash testing and ratings, we won't know which ones are really safe. Come 2015 and things might improve.