It should be. The current owner has had it since the late 90s and only put on about 13k miles. Current mileage is 132k.
It is a local car that has been well-maintained and used as a show car (2nd place BMWs of the 1980s at this year's Badger Bimmers car show) and a track car.
The interior is pretty good. The front seats have been swapped. There are no dash cracks. All of the electrics work (other than the driver's headrest adjustment and the passenger mirror, in one direction, but both can be adjusted manually).
Here is the ad:
1988 M5. 131k miles. Heated garage, custom cover. Fully documented.
Black w/factory Motorsport pin-striping. Tan full leather interior, heated
power sport seats. 298 hp, Dinan chip, Fahey crank hub, K&N air filter,
Koni adjustable front shocks. Great a/c and heater. Full tool set. Stainless
steel braided brake hoses. Race harness prepared. MetalMaster and street
brake pads. New battery, radiator, clutch master cylinder, water pump,
cooling fan, cooling and fuel hoses. New instrument computer board.
Gorgeous paint, no dings, no repaint ever. Slight cracking of front seats
otherwise pristine. All electronics in good working order.