The BMW 3-Series has been considered a benchmark sedan for decades. The 3-Series is offered with a wide array of powertrain choices including four-cylinder gas (320i, 330i) four-cylinder diesel (328d), inline six-cylinder (340i, M3), and hybrid gas/electric (330e). Most models offer BMW's optional xDrive all-wheel-drive system. Base prices on 3-Series models can be misleading due to the fact that commonly included standard equipment like heated seats or leather upholstery are options which add quickly to the price. The BMW 3-Series sedan is now part of a larger family of vehicles including the 4-Series coupe/convertible, 4-Series Gran Coupe four-door, 3-Series Gran Turismo five-door, and also the X4 crossover fastback.