A Nitro R/C is obviously louder than an electric car, but I run mine often around my neighborhood and nobody complains at all. When you're inside and not paying attention, you often don't even notice that someone is running a Nitro car. I wouldn't worry about that aspect of it. Remember that a Nitro car also runs on a battery. You have a receiver battery pack that allows the receiver in the car to accept the radio signal and the batteries in your handheld radio that send the signal to the car. So you still need batteries and charger etc as well as fuel, after run oil, air filter oil etc. (maintenance items)
For something just to drive around I'd look at an HPI RS4, Traxxis 4Tec or something similar. These are RTR or Ready to Race meaning they come built with an engine installed and radio. These typically fall in the range of $300 -$400 depending on the brand. Other cars that are available RTR are Team Magic G4S, Kyosho FW-05 etc. The Team Magic G4S is belt driven which is considered to be a little better if you ever want to race at a club locally at some point. The others are Shaft driven which induces a bit of torque steer to the car. Not a problem for bashing around, but for a controlled race environment you want a belt car if you want to be more stable. The Team Magic G4S RTR can be upgraded to the "pro" race version quite easily while the other cars are not able to be upgraded to any race parts that I know of. What I mean by race parts are carbon fiber parts, and various parts that are offered in a lightweight version and have tighter tolerances and are designed for competition. The Team magic car can also handle high performance race engines on the chassis.
If you want something serious that you have to build and want options on, then you would be spending a lot more money and have a car that is built to race specs. These include the Kyosho V-One RRR, Mugen Seiki MTX-4R, Serpent 733, XRay NT1 etc. These cars are sold as kits that you must build from the ground up and have to buy everything separately including the engine and exhaust, radio system, servos, and tools and oil required to build it. In the end you will have a much better car than any RTR but a much higher entry price. The kits with no engine or electronic parts or radio system cost anywhere between $400 - $500 depending on the model.
There's a lot of options, but remember one thing that I tell everyone. Every hobby store sells Traxxis parts so if something breaks you can pretty much walk into anyplace and find a part and they're easy to get fast online as well. The other cars especially the team magic may not have a lot of parts available easily so even though the car is better IMO, the parts available for it are harder to come by unless you want and don't mind ordering them online from somewhere. They are readily available online, but you'd be without a car until you have the parts delivered. I like to have parts on hand that I know break all the time, this is a good practice.