Jeremy was in a head-on collision according to The Mirror:

He suffered minor injuries to his legs, hand and back in the head-on collision during filming for the BBC show.

Clarkson, 48, said: “My right index finger looked like a burst sausage, my left shin was fatter than my thigh and my back felt like someone had driven over it with a pile-driver.”

The Mirror also has a quote though from Jeremy’s wife: “My husband is fine”. Whew.

Thanks to diti for the tip.