Especially if you
Look after it.
Use it sparingly and frugally
Make it available to others.
Share lifts.
I’ve managed with a low mileage hatchback for 10 years that does 60+ mpg and about 1500 miles a year. I’m not about to spend any money in a new car. I’m just going to drive even less if I can.
The best car for the environment is the one you currently have.