Tesla has a goal 20 million cars in 2030 and a goal of 50% more cars every year. I think the following progression is reasonable.
2021 900K new cars, 1.9 million total cars
2022 1.7 M new cars, 3.6 million total cars
2023 3M new cars, 6.6 million total cars
2024 5M new cars, 11.6 million total cars
2025 8.4M new cars, 20 million total cars
2026 13M new cars, 33 million total cars
2027 19M new cars, 52M total cars
2028 25M new cars, 77M total cars
2029 32M new cars, 108M total cars
2030 40M new cars, 148M total cars
Solar and fixed storage would also increase. The Tesla Semi is actually the bigger potential for CO2 and pollution avoidance. Trucks generate 70% of vehicle pollution. In 2030, Tesla would be helping to avoid in the ballpark of 3-5 billion tons of CO2 per year. This would be about 1 billion tons of CO2 from the fleet of cars and about 2 billion tons of CO2 from the trucks and then another 1-2 billion from the solar and fixed battery storage. The Tesla electric car impact is not just the increase from a fleet of 1M in 2020 to around 148M in 2030. There is also the replacement of pickup trucks and vans, which are more polluting than the current replacement of sedans and small crossovers SUVs.