Car rental is quite expensive, and, with congested traffic and parking problems, is not a good choice within the city, though you may wish to use a car to explore places in the environs (see Day Trips from Dublin on pages 66 78).
Car rentals are a good idea when exploring outside of the city.
Today, a tour of the capital takes you through a mixture of imposing ministries and embassies, modern office buildings and hotels, and along the Old Delhi of vibrant Hindu and Muslim communities crowding in on the Mughal monuments.