The manufacturer had planned to introduce the ECO Start-Stop technology in the UK from October, in line with the rest of Europe.
It now expects to have the first cars in UK showrooms from next Spring, badged Blue Efficiency.
Available on the 1.5 and 1.7 litre petrol models, Mercedes-Benz claim its Eco Start Stop offers up to a 9% improvement in fuel economy.
Diesel-powered Blue Efficiency models, which do not feature start-stop, will be offered from October as planned.
The A160 CDI Blue Efficiency has the lowest emissions and fuel consumption of any Mercedes ever sold, at 116g/km and 64.2mpg respectively.