How do I get the water out of my 2008 Solara which sloshes around when I make a turn?

Find and clear of debris all the body drain lines, usually from the door post through the inner fender, or from the windshield cowl, or trunk and door weatherstripping. If they get fouled with leaves and such water can back up inside those body panels.

Look in your spare tire compartment, mine was full of water.