Fully appreciate all the responses regarding braking distances and tyres etc...The tyres are dunlop (only had the car a week and thats what was already on it, not sure what model) Yes i did try releasing the brake and trying to steer towards the grass verge, nothing made any difference, if anything the car gathered momentum throughout.
Suppose its hard to quantify but trust me when i say this definitely did not feel like a misjudge of conditions. I was only doing 15MPH!!!! with loads of extra braking distance.
The car went straight back to lexus for a thourough inspection. They have lent me an IS250 which is very nice whilst driving this home i tried to recreate the scenario by driving down icy hills and braking hard but i could not get it even close. I went back to the scene of the accident in my company van the same morning (same conditions) and that also had no problems stopping, Citroen Berlingo outperforms Lexus? I have also driven the IS down the same road this morning (far icier!!) without any problems.....
One thing they have already said is that you do not feel the ABS braking on the 400H due to the regen braking on the motors...dont suppose anyone can confirm this to me can they?
My dilemma now is this, if they return it to me with no fault found, i dont think i have the confidence in the car to feel safe driving it in such conditions. Every car i have ever driven would have performed better in that scenario, so why was my 400h so bad?