PPI

Technical Information and Restoration Parts for the 928

Pre-purchase Inspection

As is customary it is important to do a through inspection before purchasing a car. The high performance of a 928 requires a careful inspection of a number of systems and when over looked can result in costly repairs. Consideration should be given to the model year as well since each year had unique features and improvements.

Check List

The inspection check list is broken down into five components - Engine, Running Gear, Electrical, Body, Interior and finally wraps up with the Test Drive. Each section gets a rating or points. A maximum of 1000 points are are awarded for the "perfect car". Points are deducted from the starting total that approximate the cost of repairs. From the total score a percentage is derived that can be used against the average price to determine a fair selling price.

Based on the cost of repairs is possible to come up with a negative price. In these cases the value of the car is determined for the value of parts.

Mileage

It is not uncommon to see many 928's with less 15,000 per year. Based on this average a low mileage 1980 would have under 300K on the clock. We have seen very few 928s with much over 125K miles and often in very bad shape as a result. A better standard for a pre 1985 car would be 5000 miles per year and for a post 1985 would be 7000 a year. The lower gear ratio and better interior construction of the later cars allows the higher number.

Deduct one point for each mileage increment for each year. As example a 1980 model should have 100K by 2000. Deduct 10 points for each 5000 miles over this mark and add 10 points for each 5000 miles.

Base Price

The base model price is predicated on the "perfect car" and a score of 1000 points. The final price is then determined as a percentage of the score from 1000 points

78 to 82 - $10 per point

83 to 84 - $12 per point

S4          - $20 per point

GT         - $30 per point

GTS        - $40 per point

These numbers are not absolute and are meant to approximate retail price from a dealer. Cars sold by private parties generally sell closer to wholesale value. Typically there is about a 20% difference between wholesale and retail.

As the 928 approaches very low mileage the value increases exponentially. Where the average car becomes a commodity item, very low mileage or frame up restorations fall into the one of a kind class and thus are less predictable in price.