Modern cars offer a long list of safety systems. The evidence for their effectiveness varies considerably.
Strong evidence
Electronic stability control. Detects a skid and brakes individual wheels to correct it. Studies attribute large reductions in single-vehicle crashes to it, and it has been mandatory in many markets for years.
Autonomous emergency braking. Detects an imminent collision and brakes if the driver does not. Insurance data shows meaningful reductions in rear-end collisions.
Both of these intervene when a driver has already failed, which is why they work.
Reasonable evidence
Blind spot monitoring, associated with reductions in lane-change crashes.
Reversing cameras, which reduce low-speed collisions and particularly incidents involving children behind vehicles.
Lane departure warning, with more mixed results – effectiveness depends heavily on whether drivers leave it enabled, and many disable it because it is irritating.
Less clear
Adaptive cruise control, which is a convenience feature. Some evidence suggests it may increase following distances and some suggests it encourages inattention.
Lane centring, similarly. These reduce driver workload, which is not the same as reducing crashes, and there is evidence of drivers over-relying on them.
What matters most
Crash test performance, which is published by independent bodies and covers what happens when prevention fails.
And the basics: seatbelts, correctly fitted child seats, head restraints at the right height. These have larger effects than any electronic system and are frequently done wrong.