An equivalent of Uber should be run by Transport for London, Tube travel should be free and there should be "e-scooters for everyone" to cut carbon emissions, a think-tank said.
The Away with All Cars report by Common Wealth, along with campaign groups We Own It and Greenpeace UK, says London should have no private cars by 2030.
TfL said it was investing £2.3bn to ensure 80% of journeys were by walking, cycling or public transport by 2041.
The RAC said many people needed cars.
The report says the number of cars in the UK has grown in every year since the end of World War Two, and increasing distances were travelled by car, making transport the "UK's largest sectoral source of carbon emissions".
It says that even though London is "consistently ranked in the top 10 cities worldwide for high-quality public transport", it is also the most congested and one of the most polluted cities in the UK.
To counteract this, the report says private cars should have "disappeared from Greater London" by 2030 with alternatives being accessible on a TfL app, including walking routes, buses free for Londoners, tram and Tubes, E-bikes, e-scooters, car shares and e-rickshaws.
Caroline Russell, Green Party member of the London Assembly, described "everything in this report" as "possible".
"We need major change like this to tackle the climate and air pollution crises," she added.
A TfL spokesperson said: "We're investing a record £2.3bn in creating healthier streets where walking, cycling and public transport are the natural choice for all journeys and we want 80% of journeys to be made in these ways by 2041."
Nicholas Lyes, RAC head of roads policy, said many private car journeys in London were "driven by need, rather than choice".
He added: "Our own data suggests that 72% of Londoners say they would find it very difficult to adjust to life without using their vehicles."