hymie - any solicitor instructed on an rta claim of this nature is likely to be on a no win no fee basis. i'm a solicitor and the majority of my clients' cases are funded in this way. we are not an "outfit", and you're confusing Solicitors with claims management companies that advertise on tv and then sell your details to solicitors.
as for the accident, make sure her passengers don't try to claim whiplash - and if they do they'll be subject to a 25% reduction for contributory negligence for not wearing a seatbelt. what advice has your solicitor given you? is it your solicitor in your claim that wants to agre 50/50 or is it you motor insurers that want to agree that? make sure your solicitor has been in touch with your insurers about the accident and told them not to agree any split on liability without discussing with them first.
sounds like a "low velocity impact" claim anyway i only travelling 5mph although i have to say, i have seen some genuinely badly injured people from low speed accidents.
good luck with it all