Prior to mid 1970s cheap gas, huge V8 cars. 1975-1985 expensive gas, you switch to smaller 4 cylinder cars. 90-2000 cheap gas again, everyone buys SUVs. 2001+, expensive gas again, you dump your SUV -that still works fine- because of gas prices and buy a 4 or at most 6 cylinder car. I forecast that maybe 10 years on, oil will be cheap again, and everyone will buy huge cars and dump their econoboxes.