i think vios 2nd resale value not so high, y?

because i currently use vios type 'S', bought & registered on Jan/2008, OTR RM88100.

renew insurance on this year Jan/2010, agent insurance advised market price was RM68000 and sum-insured with it.

just 2 years old my vios, now lost value RM88100-68000 = RM20100.

this is quite lot, pls comment comment, thanks in advance.