Xa rumble sound

noises
scion
xa

#1

Recently my Scion xa has been making this odd rumble noise while sitting at stoplights or even at drive-thrus. I’m not sitting idle for extended periods of time and several passengers have mentioned the noise. It almost makes the car jolt a little as well. It’s a 2006, purchased brand new with about 30k miles on it. I keep it maintained well. Can anyone give me some insight on this please?