What is the id and detail of the vehicle used in lessons for most of the times ?
SELECT T1.vehicle_id ,  T1.vehicle_details FROM Vehicles AS T1 JOIN Lessons AS T2 ON T1.vehicle_id   =   T2.vehicle_id GROUP BY T1.vehicle_id ORDER BY count ( * )  DESC LIMIT 1
vehicle used in lessons for most of the times refers to MAX(COUNT(lessons.vehicle_id)); id and detail of the vehicle refers to vehicle_id and vehicle_details;