* Auto sector gains on strong U.S. sales * Trading remains choppy ahead of macro data, Olympics decision * BOJ expected to stand pat on policy By Ayai Tomisawa TOKYO, Sept 5 (Reuters) - Japan's Nikkei share average was steady on Thursday morning as investors awaited key events this week, including U.S. jobs data and a decision on Tokyo's bid to host the 2020 Summer Olympics, while the auto sector outperformed on the back of strong U.S. auto sales. The benchmark Nikkei was flat at 14,054.05 in mid-morning trade, after rising as high as 14,140.20 at the open, its highest level since Aug. 7. It later briefly dipped into negative territory. "Strong car sales in the U.S. has again lifted market confidence in its economy, and it lifted expectations that the U.S. Federal Reserve will start cutting back its stimulus this month," said Isao Kubo, an equity strategist at Nissay Asset Management. "There is a sense of caution in the market." The broader Topix was flat at 1,156.55. U.S. payroll data for August is due out on Friday and on Saturday, a final decision on which city will host the 2020 Summer Olympics is expected. Tokyo is competing against Istanbul and Madrid. Japan's revised second quarter GDP growth numbers are also due out on Monday. A recent run of strong U.S. data has reignited speculation that the Federal Reserve will start to trim its bond-buying programme - a major driver or riskier assets in recent years - later this month. Friday's job's report is seen as a key to the Fed's tapering timeline. Automakers with high exposure to the U.S. market gained as U.S. auto sales rose at their fastest pace in nearly six years in August. Honda Motor Co gained 2.0 percent, Toyota Motor Corp added 0.8 percent, and Fuji Heavy Industries Ltd, which makes Subaru cars, advanced 1.0 percent. "Among auto stocks, Honda is benefiting the most on hopes that the company's new model Fit will fare well in the U.S.," said Yoshihiro Okumura, an analyst at Chibagin Securities. "Toyota's strength in America as well as Subaru's strong sales were widely expected." On Thursday, the Bank of Japan, which launched a massive monetary stimulus in April, is expected to maintain its policy settings with indicators suggesting the programme is working. The index has surged 35 percent this year, underpinned by the BOJ's and government's stimulus policies, but is 12 percent below its May peak.