The weaker rand did not do much to bolster vehicle exports last month, as data released on Thursday showed exports were the worst in three years.
The National Association of Automobile Manufacturers of SA (Naamsa) said SA had exported 17,391 vehicles last month, compared with 21,833 a year ago. This had slowed from 22,190 in December 2013.
Nicholas Nkosi, head of vehicle asset finance at Standard Bank, said not too much should be read into the December export numbers due to the holiday period.
"We still expect positive growth in 2016," he said.
New vehicle sales fell 7.6% year-on-year and 4.1% for the year as a whole. Naamsa said this was the second year in a row sales had declined.
It blamed the slowdown on the economy, interest rate hikes and less disposable income among consumers.
Naamsa said last year had "turned out to be a difficult year for the industry".
Sales were under pressure despite "attractive incentives".
However, the association said car rentals had offered some relief to the industry, accounting for an estimated 12.5% of new car sales during the year.
Naamsa expects total sales for this year to come in at 598,200 - the lowest number in five years.
Nkosi said increases in new vehicle prices had outpaced inflation and had been driven by the exchange rate.
"(This) puts more pressure on consumers' affordability, already under strain with rising interest rates and inflation," he said. "We anticipate that the pressure we saw in 2015 will continue through 2016."
Naamsa said the weaker rand would cause inflation to rise, adding to price hikes. "The impact of the severe drought throughout the country will also negatively affect economic growth," it said.
"Expectations of further increases in interest rates and administered prices - electricity, water, fuel - will further pressurise personal disposable income."
Vehicle sales would normalise only when price increases came in below inflation, said Nkosi.
"Economic growth to boost employment would also help, with people entering the labour market and buying cars," he said.