when you start to design project on interface for automobile mechanics that used by the mechanics to look up various fixes and parts for any number

when you start to design project on interface for automobile mechanics that used by the mechanics to look up various fixes and parts for any number of makes or models of automobiles that may come through their garage. what usability measures would be most motivating when designing this interface and what unique challenges you would have to plan for when designing an interface for an automotive repair shop.
Physical, cognitive, perceptual, personality, and cultural differences introduce challenges when designing universally usable products.whcih area from the list above and describe why it is the biggest challenge to overcome when creating universally usable designs.