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* Gasoline fuels US inflation, but underlying trend weakens

* Ford rises on plans to double production of pickup trucks

* Citi rises on management changes

* Spirit Airlines slips on revenue outlook cut

* Indexes up: Dow 0.22%, S&P 0.33%, Nasdaq 0.49%

Sept 13 (Reuters) - Wall Street's main indexes gained on Wednesday as data showing a moderate increase in consumer prices in August cemented bets the Federal Reserve could leave interest rates unchanged in September.

Major megacap growth stocks including Tesla, Meta Platforms, Microsoft and Amazon.com gained between 1.1% and 2%, with U.S. Treasury yields coming off the day's highs.

Consumer discretionary was among the top S&P 500 sector gainers as Ford Motor jumped 2.8% on plans to double the production of its hybrid F-150 pickup trucks in 2024.

Data showed consumer prices increased by the most in 14 months in August as gasoline prices surged, but the annual rise in underlying inflation was the smallest in nearly two years.

Gasoline prices, which have stoked inflation worries, peaked at $3.984 per gallon in the third week of the month, compared with $3.676 per gallon during the same period in July.

"There was the expectation that we were going to see the rise (in) headline number because of oil and gas prices and sure enough, that was spot on to expectations," said Victoria Fernandez, chief market strategist at Crossmark Global Investment.

"I don't think the Fed wants to throw a shock and do a 25-basis-point hike when the expectations are that they won't, but rate hikes are not completely off the table for the rest of the year."

Traders see a 97% chance of the Fed holding rates in September, but a 61% likelihood of a pause in November, according to the CME FedWatch Tool.

Stickiness in services inflation has kept alive prospects of a November hike.

The Fed is likely to cut rates only from April-June next year, a Reuters poll showed.

Investors will now shift focus to August producer prices and retail sales data on Thursday ahead of the Fed's Sept. 20 policy decision.

At 12:22 a.m. ET, the Dow Jones Industrial Average was up 75.00 points, or 0.22%, at 34,720.99, the S&P 500 was up 14.57 points, or 0.33%, at 4,476.47, and the Nasdaq Composite was up 68.08 points, or 0.49%, at 13,841.70.

Citigroup rose 1.6% after CEO Jane Fraser announced a major management re-organization that will result in more job cuts and give her greater direct oversight over the company as she seeks to simplify its structure.

U.S.-listed shares of Chinese electric-vehicle makers Nio and Xpeng fell 1.9% and 3.7%, respectively, after the European Commission started an investigation to assess whether their vehicles warrant punitive tariffs.

Sprit Airlines lost 2.5% as the low-cost carrier cut its third-quarter revenue outlook to reflect rising fuel prices.

Moderna gained 3.2% after the drugmaker said its flu vaccine mRNA-1010 met the primary goal in a late-stage trial. The firm also announced it was scaling down manufacturing of its COVID-19 vaccine.

Declining issues outnumbered advancers by a 1.28-to-1 ratio on the NYSE and by a 1.19-to-1 ratio on the Nasdaq.

The S&P index recorded nine new 52-week highs and the same number of new lows, while the Nasdaq recorded 14 new highs and 131 new lows.

(Reporting by Ankika Biswas, Shristi Achar A and Shubham Batra in Bengaluru; Editing by Savio D'Souza and Vinay Dwivedi)