Retail sales in the United States, a motor of growth, slowed unexpectedly in September as Americans bought less gasoline, and shopped and dined out less, according to government figures released on Monday.

Auto sales were a bright spot, however, making the difference between a negative and a positive month, the Commerce Department report showed.

The result put a lackluster finish on the third quarter and should factor into GDP calculations due later this month.

Total retail sales gained 0.1 per cent in September to a seasonally-adjusted $509 billion (Dh1.9 trillion), marking the eighth consecutive monthly increase, the department said.

But economists had been expecting a far larger 0.6 per cent gain.

Even with the modest gain, the result put the retail sector up 4.7 per cent over September of last year.

Autos sales rose 0.8 per cent, more than making up from the dip in August, but sales at gas stations fell 0.8 per cent.

Excluding the volatile auto sector, monthly retail sales fell 0.1 per cent, also undershooting analysts’ forecasts for a 0.4 per cent gain.

In addition to flagging fuel sales, the monthly number was dragged down by declining business at bars and restaurants, department and grocery stores as well as health and beauty stores.

On the other hand furniture, electronics, building supply and clothing outlets all rose.

And “non-store” retailers like Amazon continued their upward march, adding 1.1 per cent in sales volume, putting that sector up more than 11 per cent year-on-year.