The main differences between BMW's gas-powered and diesel-powered 5-Series cars are their performance, certain aspects of engine construction, starting prices, and required maintenance. BMW only offers one diesel engine for its 5-Series, a 3-liter, turbocharged six-cylinder engine that produces 255 horsepower and 413 pound-feet of torque. The gas-powered, 3-liter, turbocharged six-cylinder engine BMW offers for the 5-Series has two turbochargers, as opposed to the diesel's one, and produces 300 horsepower and 300 pound-feet of torque.
BMW also offers four-cylinder and eight-cylinder gasoline engines for the 5-Series, which produce 240 horsepower and 260 pound-feet of torque, and 445 horsepower and 480 pound-feet of torque, respectively. The six-cylinder diesel car goes from 0-60 in 5.8 seconds, the gas six-cylinder in 5.7, the gas 4-cylinder in 6.1 and the gas eight-cylinder in 4.5.
The diesel 5-Series is significantly more expensive than both the four- and six-cylinder gas models. However, the diesel is more fuel efficient than the gas six-cylinder, averaging 26 miles per gallon in traffic and 38 on the highway, versus 20 mpg in traffic and 31 mpg on the highway, respectively. Additionally, the diesel engine utilizes an exhaust treatment fluid that the gas engines do not, and this fluid must be replaced with each oil change.