1999 BMW 5 series Unknown

Very good condition 540i BMW with 136,000 miles on the body but about 60,000 on new motor. I bought this from a local import car mechanic and everything on this car has been either fixed, replaced or gone over, has a small half a dollar size surface rust by trunk lid as I was told is common in BMW's to rust there and small surface lower rust on right door but its 1999 and we live in Chicago. I would drive this car to California and back so its a great running car. Clean title, has everything loaded, new tires and super fast!! , , Here is the deal I'm looking to get $6000 OBO cash for it as Kelly Blue Books shows $6600 in good condition and $5700 in fair I feel it right in the middle so I'm willing to trade straight up for a 2000 or newer or low miles SUV, Mini Van, Larger Truck(pick up or suburban), multi passenger van for a new business i'm opening and not needing a sporty car.