Toyota 4Runner is one of the few midsize SUVs built on a truck-based platform, even though many others in the class moved to more comfortable car-based platforms. When it was new, reviewers said the 4Runner was one of the most capable off-road SUVs on the market. The base engine is a four-cylinder, though most reviewers tested the available V6, which delivers adequate power for daily driving and off-roading. Rear-wheel drive comes standard, and part- and full-time four-wheel drive systems were available. With rear-wheel drive and the four-cylinder engine, the 4Runner achieves 18/23 mpg city/highway, which is about average for the class. Upgrading to the V6 engine with more than 100 additional horsepower takes a small toll on fuel economy.