Is it a real Highline?
That’s easy: it must have one of the following two options listed in its VO (Vehicle Order), which is obtainable by VIN:
- S447A High Line interior lining
- S448A High-line Rear Equipment
You can check the factory options (VO) by VIN here: https://decoder.bvzine.com/
What about mileage?
While no car is safe from odometer rollbacks, it seems that nowadays the E32 is reasonably safe in that regard. However, it is possible (and very easy) to swap an entire instrument cluster (or the small chip in the back of the cluster) from another E32 that shows lower mileage. There is a way to catch this though! Just enter the “test” displays by holding the right instrument cluster button while turning the ignition on. Look for “F. G. NR.”: that should show you the last 7 digits of the VIN. That VIN is stored in the chip in the back of the instrument cluster, so if the chip (or the whole cluster) is swapped, the VIN will not match the car. More info here: http://bmwe32.masscom.net/johan/299960/299960.html
“Upgrades”?
It is generally considered that cars in 100% stock condition are most authentic and have the highest value. Any “upgrades” generally lower the value of collectible cars, regardless of how much they improve the aesthetics or mechanics of the car. So when you’re on the lookout for buying an E32, it’s best to look for cars that have not been modified at all from their factory condition. Even something as awesome as a manual transmission swap into a Highline would probably decrease the value of the car on the collectible car market.