In the event of an accident, how does a classic vehicle compare to a modern machine?
Badly.
Are safety features on new vehicles really a life saver?
Yes.
Can anything be done to improve the safety of classic vehicles?
There are certainly safety improvements that can be made. You can fit better brakes and tyres. You can sometimes retrofit collapsible steering colums. You can fit better seat/restraint systems to better secure the occupants during a crash (it's geneally better in terms of peak decelleration experienced by your body during a crash to be tightly strapped in than to fly forward).
What you can't really do much about is the behaviour of the body/chassis during a crash with a hard object. Modern cars are designed so that the area in front of the people crumples while the area the people are enclosed in remains solid reducing the peak decelleration experienced by the occupants and making sure they don't get crushed by the collapsing car.
Are classics safe enough to be used as a daily driver?
That really depends on your risk tolerance. People used to drive those cars all the time when they were new. Most of them survived but a significantly larger proportion than today got killed or seriously injured in accidents.
