Figures from the Society of the Irish Motor Industry (SIMI) suggest new car registrations for March were down 63% when compared to a year earlier.
Registrations dropped to 6,174 from 16,687 in the 12-month period.
Registrations for the year to date are also down by 20.5% on the same period for 2019.
Light Commercials Vehicles were down 52.9% when compared to March last year.
While Heavy Goods Vehicles bucked the trend, and saw an increase of 17.67% in comparison to March.
Used cars for March also saw a decrease of 48.1% to 4,656.
Brian Cooke, SIMI director-general said: "The health of our nation is the overriding priority.
"The motor industry will assist the State in any way we can during this pandemic.
"While showrooms, service and other activities within the industry are closed, members are available to assist in emergency call-out or delivery services.
"This will be vital in keeping essential and emergency services moving."
Mr Cooke added: "The motor industry and its employees, like so many industries, is feeling the devastating impact of COVID-19.
"Even before the crisis commenced, the new car market was in decline, and this fall has accelerated rapidly in the last fortnight with new car activity down nearly two-thirds on last year.
"Whatever the duration of this crisis, once we emerge, we will need to see decisive and ambitious action from Government to protect the nearly 50,000 jobs in our sector."