Vibrating noise from 2009 Subaru Legacy

2009 Subaru 2.5i legacy limited mileage 1,18,000+ approximately
Buying from a dealer, when you press the gas and on the course of initial pickup I get Sounds like engine vibrating noise but after the initial pick up it goes away and came back one more time after we stopped at the light, no other types of noises. He also stated the car Hasn’t been turned on for a long time, is that the case or might there be other underlying issues.

My top of the head guess would be a vibrating heat shield but a guess is all it is.

Then tell him to fix it and call you when it is ready . It is silly to buy a used vehicle with problems that might be expensive.