I'm going to say that is not a factor. Cars are actually not lighter today than they were 50 years ago. There is video out there of a IIHS crash test of a 2009 Chevy and a 1959 Chevy in an off-set collision. The 2009 busted into a million pieces, but the driver would have lived. The 1959 busted up, too, and the driver would have died instantly.
I looked into it further. The 1959 looked bigger and heavier, but that was due to perception. It was slightly longer, but no higher, and no wider.
It was also within 200 lbs of the 2009 Chevy in weight.
The weight difference between the two cars was insignificant in the crash.
1959 Bel Air 4-door
Weight (varies) 3,615 to 3,660 lbs.
Length - 210.5 inches (17' 6.5").
Width 79.9" (6' 7.9").
Height 54'-56'.
2009 Malibu:
weight: 3,415 lbs (200-245 lbs lighter)
Length: 191.8" (15' 11.8") - 18.7" shorter.
Width 70.3" (5' 10.3") - 9.6" narrower
Height 57.1" - 1.1 to 3.1 inches taller.
Sources: Malibu http://www.edmunds.com/chevrolet/malibu/2009/sedan/features-specs/
Bel Air: http://www.oldride.com/library/1959_chevrolet_bel_air.html
Sorry, my post meant to say the 1959 was longer, but no higher and only slightly wider than the 2009.
The comparison you cited doesn’t give a full picture at all. Instead of comparing two specific car models, you’d need to compare the average 1959 car with the average 2009 car. The best-selling models for most auto manufacturers today are probably sedans that weigh a lot less than that Malibu.
The differences in braking, traction, maneuverability and acceleration (not to mention safety features) would give the 2009 the edge in any real situation.