Meguairs Gold Class shampoo is what I've been regularly using.
Link: http://www.ebay.co.uk/itm/Meguiars-Gold-Class-Car-Wash-Shampoo-Conditioner-Kent-Microfibre-Noodle-Wash/281191312435?_trksid=p2054897.c100204.m3164&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D20140407115239%26meid%3D5cac1d2b00704e0d97390cb792bb6d1c%26pid%3D100204%26prg%3D20140407115239%26rk%3D3%26rkt%3D30%26sd%3D351157818694
Has conditioner in it too, ...quite how that's a good thing for a car I have no idea though.