When should a customer be handed a lap mat?

Handing a lap mat to a customer whenever they have an "Eat In" order in their car is appropriate because it ensures that they have a clean and convenient surface to manage their food while dining in their vehicle. This practice not only enhances the customer's dining experience but also maintains cleanliness and prevents spills or messes in the car. The lap mat serves a practical purpose, making it easier for customers to enjoy their meal comfortably and without issues.

The other options do not align with the specific context that justifies the use of a lap mat. For instance, providing a lap mat solely based on a large order or a request for additional items does not necessarily enhance the experience of dining in a vehicle. Similarly, while dining with children may introduce considerations for cleanliness, it is not a standard requirement for all families, nor does it address the scenario of a customer eating in their car specifically. Thus, linking the lap mat to the context of an "Eat In" order is the most logical and beneficial approach.