A survey has found that listening to rap music on the car stereo is
more likely
to lead to road rage than any other genre (sounds fair enough, as if
you've got Eminem cranked up and some asshole cuts you off you'd feel
like bustin' some caps in the punk's ass, already being on that wavelength).
Meanwhile, "pop" (which presumably means Top-40 girl/boy bubblegum) was the
least likely to lead to road rage, being known for its tranquilising
properties. (Which is probably why you only hear Top 40 radio in shops, because
anything less mindlessly ebullient wouldn't induce people to be happy consumers
quite as effectively.)
Mind you, given that the survey was taken by an outfit named the Little Chef
restaurant, its scientific validity may be in some doubt.