Which city is known as the 'Detroit of Southern Asia'?

The car sector contributes 8% of Tamil Nadu's GDP.

About 21% of passenger automobiles and 33% of commercial vehicles manufactured in India are produced by this industry.

The city of Chennai is home to 30% of India's car sector and 35% of its auto components.

Chennai is known to be the "Detroit of Southern Asia" as a result of its industrial dominance.

Hence, the correct answer is option C, i.e., Chennai.