Since October, the majority of new cars sold in Ireland have kilometre-only speedometers, according to motor industry representatives.
The National Safety Council has advised that there is no legal obligation for motorists in older cars to convert their speedometers to kilometres only and it was also unnecessary.
Although there is no legal obligation to have kilometre-only instruments, the Society of the Irish Motor Industry (SIMI) said many car distributors decided to introduce the change because they believed it would be expected by customers.
Mr Cyril McHugh, SIMI's chief executive, said the industry had originally opposed the move to metric because of the potential additional costs, as most new Irish cars were built for the British market which still has the imperial system.
"The industry has responded admirably I think," he said. "Obviously we would have preferred things to stay the way they were . . .
"There's no legal requirement to have kilometre-only speedometers," Mr McHugh added, "but from a marketing point of view, there's not much point selling cars with speed in miles, when the signs are in kilometres per hour."
However, car dealers said yesterday that a significant number of new cars are still not in metric-only format.
Mr Michael Ahern of Gowan Motors Merrion, in Dublin, said that a small number of models in their Ballsbridge showrooms were in metric at present, but this was expected to increase following the changeover.
All new cars sold in Ireland since the mid-1980s have been required to have a dual speedometer which provides k.p.h. and m.p.h. readings, according to Mr Brian Farrell of the National Safety Council.
"We have also issued kilometre converters for the speed limits, so we are confident that people will be able to adjust quite easily," he said.
The costs of converting older cars to kilometre-only speedometers are estimated at anything between €500 to €1,000, including their fitting.
SIMI has advised anybody considering a conversion to go to a recognised car dealer, as speedometers are now integrated into various parts of the car, including the brake system.