My car lost about 25% mpg on an ongoing basis. At the same time my low oil level light came on and will not go off. The oil level is fine. It also now shakes pretty bad between 45 and 55 mpg. It doesn't feel like it is coming from the wheels. It also shakes when I'm stopped, but that is usually only after I have driven it for awhile. The last symptom is that a terrible fumey smell is happening under the hood. I cannot drive on the highway with my window down because the smell chokes me out. All of these started happening around the same time. Any thoughts?