I just purchased a '90 964 C4 Cab 3 weeks ago. It was a distress sale in southern FL. After a couple weeks negotiations, I got it for under $20k.
My car, was a creampuff w/ only 20k mi. and some nice extras such as M030 ROW suspension, full leather, everything works and it was all checked out by Champion Porsche prior to my flying down.
The thing is, mileage isn't as important as the individual car. A PPI (Pre-Purchase Inspection) is a MUST!
Don't buy the 1st one to come along, there are really quite a few to look at.
As to the PPI, it is just a guide and no guarantee. In my case, I instructed Champion that I wasn't looking so much for a total 'every hair in place' inspection, only one sufficient to tell me whether it was worth my time to fly down and see it. I also made sure they understood that this was a
'what's wrong with this car' inspection so I could use it to beat the owner down on price and also to recoup the cost of the inspection.
I am a longtime Porsche owner and current Boxster owner, so I knew what to look for and would inspect and drive the car myself prior to handing over any check. This too is important, that you actually see and drive the car. Having been a prior Porsche owner, you'll know if it's a good car or a lemon. Be mindful of the clutch and vibrations which may indicate a failing dual-mass flywheel.
Interestingly, Champion found several things which I brought to the negotiation that later proved erroneous such as; they said the radio was shot and wouldn't accept the code (turned out they had forgotten to reset the radio with a paperclip in the reset hole - works great), they said the alternator was bad (turned out they checked it after a long drive w/ the car at it's lowest idle - above 900 RPM it measures 14.2 VDC), they said the front diff was leaking badly 'Wet' was their word (turned out the car was so low miles, that the cosmolene used by Porsche to protect the metal on transoceanic crossings had not yet worn away and when hot, this substance re-liquifies - this is what they were seeing, there was no leaking at all). All these things were confirmed to be OK by a major Porsche Race mechanic in Macon, GA who arranged to see the car on my drive through because I am friends with one of his best buds. He said the car was fantastic, hadn't seen one in as good a shape. In Champion's defense, they haven't seen an aircooled car regularly for 12 years, so they may be getting a little rusty on them. That being the case, I might prefer having a recommended Porsche 'Indy' look it over rather than a dealer, but in my case, this wasn't possible.
Things to plan for are new tires (if they're more than 6 yrs. old - mine were the original OEM tires (20 y.o.!), same w/ the battery - factory original, wiper blades were shot, alignment (I did mine when I put the new tires on it).
Anyway, miles are not as important as condition and proper service records and timely maintenance.
This would include all the updates such as dual distributor breather, fuel filler tube, oil pressure valve. It would be nice to find one where the headwork has been updated (if pre-92).
Other than this, these are fairly bullet-proof. There is always an element of risk in buying a used car, and you have to expect to do some work to it, so plan on a war chest of at least $1000 to take care of all the piddly stuff so you can reset the clock and also to make the unknowns known. Good Luck!
Cheers!
