Create an interaction term Mileage*Cyl (called MileCyl). Use Mileage, Cyl, and MileCyl to predict TPrice. Does this interaction term appear to improve the model? Use residual plots and R2 to justify your answer.
While there is no “best” model, many final models developed by students in Question 21 tend to include the terms Cadillac, Convertible, and Liter. Since each of these terms is related to the Cadillac XLR-V8, it may be helpful to include an interaction term for Mileage*Cadillac, Mileage*Convertible, or Mileage*Liter. Other Mileage, Make, or Type interactions may also be helpful additions to the model.