As of 2021, the top 10 biggest car manufacturers in the world, based on production volume and market share, are:

1. Toyota – A Japanese multinational automotive manufacturer known for its popular models such as Corolla, Camry, and Hilux.
2. Volkswagen Group – A German automotive conglomerate that owns brands like Volkswagen, Audi, Porsche, and Skoda.
3. Hyundai Motor Group – A South Korean conglomerate that owns Hyundai and Kia brands.
4. General Motors – An American multinational corporation that owns brands like Chevrolet, Cadillac, GMC, and Buick.
5. Ford Motor Company – An American multinational automaker best known for its Ford and Lincoln brands.
6. Honda – A Japanese car manufacturer known for its lineup that includes the Civic, Accord, and CR-V models.
7. Stellantis – A multinational automotive corporation formed in 2021 through the merger of Fiat Chrysler Automobiles (FCA) and PSA Group. It owns brands like Jeep, Ram, Peugeot, and Citroën.
8. Nissan – A Japanese multinational automobile manufacturer that produces popular models like the Nissan Rogue, Altima, and Sentra.
9. Suzuki – A Japanese manufacturer known for its compact cars and motorcycles.
10. BMW Group – A German multinational company that produces luxury automobiles under the BMW, Mini, and Rolls-Royce brands.

It is important to note that rankings may vary slightly depending on the source and criteria used to evaluate the car manufacturers.