Which of the following is NOT a common cab configuration?

In the context of truck cab configurations, a luxury cab is not recognized as a standard type. The other configurations, such as regular cab, extended cab, and crew cab, are widely used and refer to specific designs that cater to different needs for passenger space and cargo versatility.

A regular cab is the most basic configuration, typically offering a two-door setup with a smaller interior space meant for two to three passengers. The extended cab provides additional space and is designed with rear seating areas that can accommodate more passengers or extra gear, making it suitable for those who need extra room without going to a full crew cab setup. Crew cabs are built for full-sized passenger capacity, featuring four doors and more legroom, thus allowing for comfortable seating for a larger group.

Luxury cab, on the other hand, is not a standard classification used in the industry to define truck cab types. It may imply a higher-end model with more amenities, but it does not refer to a specific configuration recognized across various truck manufacturers. Therefore, the correct answer highlights the distinction between recognized cab styles and those that are more of a marketing term rather than an established category.