The calculated distance (air line) between Saint-Germain-en-Laye and Le Mans is approximately 106 miles respectively 171 kilometers.
By car or train, the actual journey to Le Mans is certainly longer, as only the direct route (as the crow flies) between Saint-Germain-en-Laye and Le Mans has been calculated here.
Air line (approximately)
171 kilometers
92 nautical miles