The calculated distance (air line) between Lenart v Slov. Goricah and Koper is approximately 123 miles respectively 198 kilometers.
By car or train, the actual journey to Koper is certainly longer, as only the direct route (as the crow flies) between Lenart v Slov. Goricah and Koper has been calculated here.
Air line (approximately)
198 kilometers
107 nautical miles