To estimate the price of the 2015 BMW Z4 sDrive 18i with 129000 km mileage, I considered the listed prices of similar cars. The closest matches are: 1) 2015 BMW Z4 sDrive 18i with 129000 km listed for AED 55000, 2) 2015 BMW Z4 18i 2.0L I4 with 127000 km listed for AED 55000, 3) 2015 BMW Z4 S-Drive 18i 2.0L I4 with 97200 km listed for AED 65000, and 4) 2013 BMW Z4 2.0L 18i with 131000 km listed for AED 44000. The average of these prices is (55000 + 55000 + 65000 + 44000) / 4 = AED 54750. Considering the car's condition is not specified as good, I adjusted the price slightly lower.