what kind of radiator coolant is used for citroen xsara vtr 1.6 2001

Same as any other car, water and anti freeze mix.

l can concur with the other except that, new cooling systems use their own materials, so Prestone is maybe not a valid choice. water yes, but check with the owners manual for further information. good luck.

If you do not think it uses what every other car uses, then either read your handbook, or ask Citroen.
Bye the way, Chris M, says do not use Prestone, l would not either, it is a band/group!