I need some advice. I'm thinking of renting a car when I come to the city in april. Can you tell me the cost of parking in the city and also what to expect for tolls, etc.

Why would you even consider renting a car in NYC?

It's easy to get around walking, taxi or subway....the roads are packed for driving in and parking is bad and expensive.

Richard is right. Driving around NYC is insanity.
Parking is very expensive. Generally $30+/day.
And don't even think about finding parking on the street.

Take a taxi from the airport into Manhattan. Once here get around by walking, taxi, bus, or subway.

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$30 a day is if you leave the car there all day (i.e., no in and out). If you drive somewhere and park for two hours (to eat or shop), you can plan on $15 to $20. Do that a few times and it can really add up, and you're still dealing with the hassle of driving, looking for a garage, walking to and from...

renting a car to be your transportation around new york city while you vacation here is a really bad idea. you will regret it, and see it's silliness the minute you get here.

When we live in Sydney we each have a car and drive everywhere but when we lived in New York we didn't bother to get one, even though we had a parking space under our building, it is just not necessary. We hired one a couple of times when we went upstate etc. but that's all. The subway was much easier and there are always taxis around. I was surprised, I thought I would miss driving everywhere but I never even thought about it.