Normal “wear and tear” that results from the normal use of a vehicle is an inherent part of sharing or using a car. The host is never “protected” against normal interior wear and tear. Definitions of "wear and tear" and "mechanical failure" may be found here.
Guests are not “responsible” for wear and tear or mechanical failure resulting from normal usage of the car.
However, guests are fully responsible for, and Drive lah does not provide any protection to guests for:
any damage related to “misuse” or Prohibited Uses of the vehicle
serious damage to the inside of the car, including gouges, tears, and punctures
any mechanical damage resulting from a guest’s negligence, intentional acts, or improper driving (e.g, clutch damage from rough driving, suspension damage from running over speed bumps at high speed or into curbs, etc).