Quick, agile and well-appointed, this iteration of the BMW X5 was available with either gasoline or diesel powerplants, so we tested one of each. Base models were updated with a turbocharged six-cylinder engine and an eight-speed automatic transmission. This brought improved acceleration and fuel economy. The X5 is sporty to drive, with capable braking and handling. But a stiff and choppy ride counts against it. Overly heavy steering can also be a hindrance at low speeds, or when parking. Some controls are confusing too. The third-row seat is suited only for children.