if i had won that kind of money, i would simply invest in rebuilding the engine in my sonic, and make it a powerful and reliable 1.8 Turbo engine, upgrade and reinforce all the parts on the car so they would last longer, repaint the car to a color scheme of my choice, and completely upgrade the interior with new upolster and speakers, plastic colors and such. Air Ride suspension for Low riding when want low, and regular height when dont want low.
basically i would deck out my sonic and enjoy what i already have. Still be riding in something fun, reliable, small for tight spots, and can continue to put a smile on the face even if its not a high dollar $50k Plus vehicle. even tho after all those upgrades it probably would be then ha ha.
thats what i would do if i had won $5M.