The calculated distance (air line) between Retiro and Rivas-Vaciamadrid is approximately 11 miles respectively 18 kilometers.
By car or train, the actual journey to Rivas-Vaciamadrid is certainly longer, as only the direct route (as the crow flies) between Retiro and Rivas-Vaciamadrid has been calculated here.
Air line (approximately)
18 kilometers
9 nautical miles