My 2010 Sonata has 25k miles on it and I noticed with any car I've bought, regardless of make/model, when I park it, I hear pinging for a while from somewhere under the car. It sounds like the metal of the frame is contracting after running hot/warm. Any ideas why this happens?

Matthew

 

It is cool air on hot exhaust pipe metal..

Similar effect would be to fill milk jug with really hot water, hurry and pour it out, put lid on, and watch the jug contract and make crunchy noises..

Some cars it will actually sound like somebody tapping pipe firmly with a screwdriver, loud TINK/CRACKING sound randomly after engine shut off.

Walk away and carry on, it'll stop when it cools off.

 

Yep! What he said. My Suzuki Aerio still rings like a bell (115,500 miles on factory exhaust), after a run down the interstate.

 

I noticed that my car makes noise when it is still running and parked. Is that normal?

 

Could be. With the engine in operation, there's a lot of other things in 'motion'.... fuel pump & injectors, power steering pump, alternator, water pump, idler pulleys & belt tensioners tend to make some noise, air conditioning compressor, electric fan(s), auto trans pump...

There's a lot that can make noise.

 

This sort of noise is amplified if any of the spot welds holding shields are broke or if any of the hangers are loose. You can poke around the exhaust underneath with a long screw driver and figure out pretty quickly where the noise is coming from. A good set of ramps helps.