People can be a bit strange about letting anyone else dig around their car - especially mechanics! It does ring bells with me too and I usually tell my cleints to walk away from a deal if the seller won't allow a PPI.
The car has sat around for a couple of years on the market - that rings more warning bells with me (along with your pics).
Also, I am seriously concerned about the safe driveability of this beast. You sure you're up to a turbocharged 3.0L? It could have an awful lot of lag which will get you into big trouble in no time flat (usually in the middle of a corner when the boost finally decides to kick in).
However, I still consider it is a good exercise for you to go through. This car has got under your skin and you need to go through due process to get it out of your system
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