A concept car is a car made to showcase new styling and/or new technology. It is a foundational concept or the vehicles basic structure as designed on the drawing board or design sketch. Concept cars are often exhibited at motor shows to gauge customer reaction to new and radical designs which may or may not be mass-produced. They are created by car-makers to measure feedback on the styling and to decide if the design should be adapted for the final version or if it should be scrapped altogether. Concept cars never go into production directly, and in modern times, all would have to undergo many changes before the design is finalized for the sake of practicality, safety, regulatory compliance, and cost. A "production-intent" prototype, as opposed to a concept vehicle, serves this purpose. Concept cars are often radical in engine or design, and some use non-traditional, exotic, or expensive materials, ranging from paper to carbon fiber to refined alloys. They can have unique layouts, such as gullwing doors, 3 or 5 (or more) wheels, or special abilities not usually found on cars. Concept cars are a way for car manufacturers to test new ideas and determine what consumers want. They are also a marketing tool that can impress and provide insight into what kind of vehicle can be sold in the future.