To anyone who’s ever visited Mumbai, they are as evocative a symbol as the Gateway to India. The boxy, black-and-yellow Premier Padmini taxis have plied the city’s streets for nearly half a century, defying their old age to become a part of the fabric of this chaotic metropolis.

Now, a new city regulation is beginning to send the venerable Padmini — known as “Fiat taxis” after the Italian model they were based on — to scrap heaps. Along with them will go a piece of India’s history — and the taxis’ colorful personalized upholstery that has dazzled so many passengers that websites have sprung up to celebrate them as an art form.

A government order that all vehicles more than 20 years old be taken off the streets took effect this week, and that will take some 4,500 of the remaining 9,500 Fiat taxis out of commission as their licenses expire and are not renewed, said A.L. Quadros, head of the Mumbai taxi drivers’ union. The rest will be phased out each year they reach the 20-year mark.

For Quadros and many others, the new regulation represents the end of an era.

“This Premier Padmini is iconic,” he said, adding that people worldwide identify it with Mumbai.

The car harkens back to when India’s policy of economic self-sufficiency meant domestically produced cars were the norm. For most, the only options were the Padmini and the Ambassador, made by Kolkata-based Hindustan Motors.

The first Padminis rolled off assembly lines in 1964 at a factory in Mumbai (then called Bombay) under a license from Fiat. Within a few years, there were 62,000 of them in the Bombay’s taxi fleet alone, Quadros said.

Production stopped in 2000, but the Fiat taxi never disappeared with owners repairing the engines and replacing the interiors when they wore out.