China's electric carmaker BYD had the most complaints last year, followed by Mercedes-Benz, BMW, Buick and Audi, according to a report by the China Consumers Association.

For top 10 brands with the most complaints, prominent problems were deposits, engines, tires, suspected fraud and car paint.

Auto-related complaints in the whole industry - same for those brands mentioned above - focused on after-sales service, contract and automotive quality, which accounted for 32.2 percent, 20.7 percent and 20 percent, respectively.

Of those complaints, carmakers which failed to offer three guarantees (guarantees for repair, replacement and compensation of faulty products) and fulfill after-sales commitment took the majority in after-sales service problems, accounting for 50.1 percent and 38.3 percent, respectively.

For automobile contract complaints, deposit dispute and contract default took 32.6 percent and 22 percent, respectively, while almost half of quality complaints related to product performance (27.3 percent), non-conforming products (13.4 percent) and products which cannot use in specific environment (9.2 percent).

Last year, the association recorded 19,283 cases about complaints in auto products (including auto parts), among which family cars (62.7 percent) and auto parts (26.2 percent) took the main part, down 5.8 percent compared with a year earlier.

The trend was affected by the 4.1 percent decline in passenger car sales in 2018 on the one hand, and it was also connected with market regulator's efforts to improve the consumption climate, the report said.