I have no legal experience, but I am doing legal studies at school and this is just my thoughts on it. The key to what you and your insurance company is saying is that 'additional costs (excess) that he incurred because this was a contract between him and Hertz' I'd say your insurance company is 100% on the money with that. Car B did not take out insurance or whatever they call it on the hire of the car, which leaves him to deal with the excess that Hertz implies because he was involved in this accident. If he had of taken out the extra cover, no problems. He has no grounds to make you pay the money, I would think, his problem is with Hertz. On your second thought of him taking civil action on YOU personally, I think he's having it on and trying to put the wind up you to pay up. Your insurance company is representing you in the first instance, which will have the very best lawyers that money can buy. If he wins, he wins, your insurance company pays out the 2k. No loss to you I'm assuming? But if he looses I doubt he would continue to pursue it as a civil matter against you personally, especially after having to pay court costs for losing He'll be flat out broke from pursuing you if he loses the first instance and I can't see him continuing the fight against you, unless he has deep pockets, in which he would pay the 2k anyway. He has no 'friends' in this, if he takes the matter further, it will be out of his own pocket and probably a lot of his time And after just paying 2k in excess, its probably a pretty light pocket. Just my .02 Goodluck and keep us posted