I stumbled across this web site with a month by month long term test drive :-
http://www.carkeys.co.uk/long_term/kia_rio_15_crdi_gs/default.asp
Excellent coverage and overall assessment of the Rio
http://www.carkeys.co.uk/long_term/kia_rio_15_crdi_gs/default.asp
Excellent coverage and overall assessment of the Rio