Avoid cars with stickers and ornaments hanging from the rear-view mirror because the driver is more likely to get angry.
That's the view of researchers from Colorado State University, who claim that drivers displaying these 'territorial markings' in their vehicles are more likely to behave territorially on the road.
They defend their road space, act more aggressively when driving and are subsequently more likely to get angry if they feel that other drivers have invaded their territory.
Not so much anarchy in the UK
However, according to research carried out by insurance company Swiftcover, the good news is that drivers in the UK are less keen to mark out their territory.
The study revealed that 13% of British drivers had an ornament hanging from the rear-view mirror, 3% had car stickers and just 2% admitted to having furry dice.
We are, however, a nation of slobby drivers the same poll discovered that 50% of drivers said they keep rubbish in their car because they can't be bothered to throw it away.