I don't generally even buy a car until it's about ten years old. Still usually get about ten more years out of it without any major repairs. Average age of a car in the US is 12 years. This was a stupid plan from the beginning. Even if you are worried about the environment, keeping a car on the road is likely to be better for the environment than scrapping it and buying a new one. There is a lot of life left in them thar cars.
There are multiple dimensions to helping the environment, and sometimes what's good for one dimension can be bad for another. This is one of those cases. Yes, avoiding the carbon dioxide emissions incurred for manufacturing a car is a good thing, since the increased efficiency of a new car won't offset the car manufacturing for a long time and maybe never.
However, that's just from the perspective of greenhouse gases. There's also the separate issue of air pollution and its health effects. For that, it's clear that getting rid of old cars is a clear win. Which issue is more important? If you live in New Delhi, air pollution is a huge problem, among the worst in the world. The air pollution is so bad that it's 10-20x worse than WHO guidelines and impacts both health and longevity. Old cars is a contributor to the air pollution crisis.
Climate change is important, but it's a long-term problem with varied worldwide effects. This type of air pollution is localized and immediate. If it were me and I lived there, I'd want to address the health issue first. The only local pushback is from considering family finances and not climate change.