For which of the following is insurance not required in Indiana?

In Indiana, insurance is not required for certain types of vehicles under specific classifications. Class B Motor Driven Cycles (MDC) are typically smaller, less powerful vehicles that may not be used as frequently as regular automobiles or commercial vehicles. As a result, the state does not mandate insurance coverage for these types of cycles, recognizing that they often have lower risks associated with them compared to larger vehicles.

In contrast, regular automobiles, Class A MDC, and commercial vehicles carry a higher risk profile and are subject to insurance requirements due to their potential for greater impact in accidents and liability situations. The purpose of mandatory insurance is primarily to protect all road users and ensure that there are financial resources available for damages or injuries sustained in traffic incidents. Thus, Class B MDC does not require insurance under Indiana law, making it an exception compared to the other vehicle categories mentioned in the question.