Although most of us love heavily built cars (which includes me) there are some points to consider here
Lighter cars +ves
1. Lighter cars are peppy to drive & a joy to ride in cities
2. I guess most of the light weight cars are also the best sellers in their segments - Alto, Swift etc (mainly due to fuel efficiency)
Lighter cars -ves
1. Pedestrian safety is more of a marketing strategy than an asset - How many of us think about pedestrian safety while booking a car? We will be busy checking finance options, emi's, negotiating the price of the ICE etc.
2. Light cars cant give the confidence what the heavier cars can.
3. Road noise is more due to the thinner sheet metals
4. Tyre upgrade is a must if you want better road grip, then we lose out on the mileage factor & so the whole point of buying a lighter car for better FE is lost.
5. In any collision a lighter car will get damaged easily, less safety for its passengers
Heavier cars :- +ves
1. Safer than lighter cars - in most cases
2. Inspires confidence in the driver even at high speeds
3. Silent cabins, less road noise, nill/very little rattles
4. Better suited for ICE with woofer kind of options
5. more confortable, tougher suspensions, less bouncy feel
Heavier cars:- "-ves"
1. Most of them are low on fuel efficiency
2. They have lesser initial pickup (very evident when you find a M800 being quicker at signals than most other heavier cars)
3. They cant impress you easily on the short test drive the SA offers you in the city lanes
4. Costlier to buy, costlier on daily running (FE) &
low resale value
There are N no:of situations where the build quality of the car wont decide the safety of the passengers in it.
Sharing an incident:
One of my friend's family member was driving behind a tempo over loaded with protruding Iron rods - TMT Bars used in building house pillars etc. The tempo stopped to enter the log book at the building site gate (on a very small inclined road) & when the driver tried to drive ahead the tempo started to roll backwards & before the tempo could stop the rods broke the windshield & injured my known person very badly. Since that day my friend's family cribs that Alto is a poorly built car & that the car was not able to protect the occupant.
In the above situation it was the car driver's fault that he was too close to the vehicle ahead. In the above situation no car would be safe, even my favorite Fiat Palio would be of little/ no use.
My choice:
Fiat Palio
Anyday a heavier car, irrespective of mileage/resale value.