Chassis Quality

Why does the price (Total Cost) go UP when you lower the quality of the chassis? The tool-tip states it should decrease but I am not seeing that.
EDIT: for example, the car I am working on costs $9179.10 and 117.96 P.U. at 0 quality, at +5 it is $9992.52 & 133.13 P.U., at -5 it is $9942.95 & 116.35 P.U.
EDIT: for example, the car I am working on costs $9179.10 and 117.96 P.U. at 0 quality, at +5 it is $9992.52 & 133.13 P.U., at -5 it is $9942.95 & 116.35 P.U.