A Fault on the Motorway Crashes 5% of the Time. At a Junction, 13%.

Owners describing a fault almost always say where they were. That detail turns out to predict the outcome better than the fault itself does.

The motorway appears in eight times more complaints than junctions do and produces less than half the crash rate.

Speed is not the variable

The intuition says the fast road is the dangerous one. The data says the opposite, and the reason is what surrounds the car rather than how quickly it is going.

A motorway gives a failing vehicle almost everything it needs. Traffic moves one way, lanes are wide, there is usually a shoulder, and a car that loses power at seventy still has several hundred metres of momentum to steer with. The driver has time to make a decision.

A junction gives none of that. The failure happens with cross traffic already committed to its own path, with no shoulder, and with a decision required in under a second. Losing the engine while pulling across a road is a different problem from losing it in lane three.

Car parks and driveways sit near the top, which is stranger

Speeds there are walking pace, and yet the crash rates are 12.3% and 11.9% — more than double the motorway.

What those places have is obstacles at close range and people on foot. A car that moves unexpectedly in a car park does not need speed to hit something; everything is already within a few metres.

This is also where unintended movement concentrates — the rollaway complaints, the vehicles that crept out of driveways, the ones that went forward when reverse was selected. We found the same pattern in parking brake complaints, which record a 13.7% crash rate, the highest of any braking component.

The severity runs the other way

Crash rate is not the whole picture, and the injury figures show why.

Motorway incidents produce 5,601 injuries across 5,833 crashes — close to one injury per crash. Car park incidents produce 1,220 injuries across 2,210 crashes, roughly one per two.

So the junction and the car park are where a fault is most likely to hit something, and the motorway is where hitting something hurts most. Both facts matter and neither cancels the other.

What to do with a car that starts misbehaving

The instinct is to keep going to somewhere convenient — the next exit, the nearest car park, home.

The data argues against all three. The risk concentrates where the vehicle has to interact with cross traffic, pedestrians and obstacles at close range, which is exactly what "somewhere convenient" means.

Stopping in a straight line on a wide road, with hazards on, is the option the numbers favour. It is inconvenient and it is where the crash rate is lowest.

And if the fault is one the manufacturer already knows about, the repair is free — a free VIN check shows the open campaigns for that specific vehicle.