I swear the thing has damaged my hearing it is so loud.
The door seals are one poor design and allow air to whistle and roar through the car.
Took it back twice and they replaced the seals with no improvement. Finally ran silicon sealant around behind the seal and that has helped a lot.
Tire noise very loud.
Loud gear whine at 35 MPH and You can't shift into reverse without double clutching or hammering the stick.
Both normal per dealer.
Impossible to back up at night.
Stupid automatic headlights can not be turned off and backup lights are too weak.
Gas mileage is poorer than my Camry with same motor and tank is too small.
Max of 300 miles and it's on Empty.
We bought the car because I'd had good luck with my 2003 Camry and because the Matrix has a ton of room for hauling stuff.
Seats fold flat - even the passenger's.
The 2.4 is peppy and the seats are comfortable.
Better door seals.
Better sound insulation.
Some way to override automatic headlights other than leaving the emergency brake on.
Brighter backup lights.
Smaller side mirrors (big blind spot on left makes it hard to see when turning left.)
Better gas mileage.
Tone down the too bright Passenger Security lights.