The 6 Series has standard Active Head Restraints, which use a specially designed headrest to protect the driver and front passenger from whiplash. During a rear-end collision, the Active Head Restraints system moves the headrests forward to prevent neck and spine injuries. The GranTurismo Convertible doesn’t offer a whiplash protection system.
The 650i offers all wheel drive to maximize traction under poor conditions, especially in ice and snow. The GranTurismo Convertible doesn’t offer all wheel drive.
A passive infrared night vision system optional on the 6 Series helps the driver to more easily detect people, animals or other objects in front of the vehicle at night. Using an infrared camera to detect heat, the system then displays the image on a monitor in the dashboard. The GranTurismo Convertible doesn’t offer a night vision system.
The 6 Series’ optional lane departure warning system alerts a temporarily inattentive driver when the vehicle begins to leave its lane. The GranTurismo Convertible doesn’t offer a lane departure warning system.
The 6 Series has standard Park Distance Control to help warn drivers about vehicles, pedestrians or other obstacles behind or in front of their vehicle. The 6 Series also has a standard backup monitor to help drivers see any and all obstacles behind their vehicle, and an optional Side and Top View Cameras to allow the driver to see objects all around the vehicle. The GranTurismo Convertible doesn’t offer any parking assist system.
The 6 Series’ optional blind spot warning system uses digital cameras monitored by computer to alert the driver to moving objects in the vehicle’s blind spots where the side view mirrors don’t reveal them. The GranTurismo Convertible doesn’t offer a system to reveal objects in the driver’s blind spots.
The 6 Series has standard BMW Assist, which uses a global positioning satellite (GPS) receiver and a cellular system to remotely unlock your doors if you lock your keys in, help track down your vehicle if it’s stolen or send emergency personnel to the scene if any airbags deploy. The GranTurismo Convertible doesn’t offer a GPS response system, only a navigation computer with no live response for emergencies, so if you’re involved in an accident and you’re incapacitated help may not come as quickly.
Both the 6 Series and the GranTurismo Convertible have standard driver and passenger frontal airbags, front side-impact airbags, side-impact head airbags, front seatbelt pretensioners, four-wheel antilock brakes, traction control and electronic stability systems to prevent skidding.
The 6 Series’ corrosion warranty is 8 years and unlimited miles longer than the GranTurismo Convertible’s (12/unlimited vs. 4/50,000).
BMW pays for scheduled maintenance on the 6 Series for 4 years and 50,000 miles. BMW will pay for oil changes, tire rotation, lubrication and any other scheduled maintenance. Maserati doesn’t pay scheduled maintenance for the GranTurismo Convertible.
There are over 6 times as many BMW dealers as there are Maserati dealers, which makes it much easier should you ever need service under the 6 Series’ warranty.
J.D. Power and Associates rated the 6 Series second among premium sporty cars in their 2012 Initial Quality Study. The GranTurismo Convertible isn’t in the top three in its category.
The 650i’s standard 4.4 turbo V8 produces 1 more horsepower (445 vs. 444) and 104 lbs.-ft. more torque (480 vs. 376) than the GranTurismo Convertible’s 4.7 DOHC V8. The M6’s standard 4.4 turbo V8 produces 116 more horsepower (560 vs. 444) and 124 lbs.-ft. more torque (500 vs. 376) than the GranTurismo Convertible’s 4.7 DOHC V8.
On the EPA test cycle the M6 gets better fuel mileage than the GranTurismo Convertible Sport Auto (14 city/20 hwy vs. 13 city/20 hwy).
Regenerative brakes improve the 6 Series’ fuel efficiency by converting inertia back into energy instead of wasting it. The GranTurismo Convertible doesn’t offer a regenerative braking system.
In heavy traffic or at stoplights the 6 Series 640i/M6’s engine automatically turns off when the vehicle is stopped, saving fuel and reducing pollution. The engine is automatically restarted when the driver gets ready to move again. (Start/Stop isn’t accounted in present EPA fuel mileage tests.) The GranTurismo Convertible doesn’t offer an automatic engine start/stop system.
The 6 Series M6’s standard fuel tank has 1.3 gallons more fuel capacity than the GranTurismo Convertible (21.1 vs. 19.8 gallons).
For better stopping power the M6’s brake rotors are larger than those on the GranTurismo Convertible:
For better traction, the M6’s tires are larger than the largest tires available on the GranTurismo Convertible (F:265/40R19 & R:295/35R19 vs. F:245/35R20 & R:285/35R20).
The 6 Series’ optional 275/30R20 rear tires provide better handling because they have a lower 30 series profile (height to width ratio) that provides a stiffer sidewall than the GranTurismo Convertible’s 35 series tires.
Changing a flat tire near traffic can be dangerous and inconvenient. The run-flat tires standard on the 6 Series can be driven up to 50 miles without any air pressure, allowing you to drive to a service station for a repair. The GranTurismo Convertible doesn’t offer run-flat tires.
The 6 Series offers an available active suspension system, which counteracts cornering forces actively, limiting body roll and improving handling and stability. Maserati doesn’t offer an active suspension on the GranTurismo Convertible.
The 6 Series has a standard driver-adjustable suspension system. It allows the driver to choose between an extra-supple ride, reducing fatigue on long trips, or a sport setting, which allows maximum control for tricky roads. The GranTurismo Convertible’s suspension doesn’t offer adjustable shock absorbers.
For better handling and stability, the average track (width between the wheels) on the 6 Series is .9 inches wider in the front and 2 inches wider in the rear than the track on the GranTurismo Convertible.
The M6 Convertible handles at .92 G’s, while the GranTurismo Convertible pulls only .88 G’s of cornering force in a Car and Driver skidpad test.
For better maneuverability, the 6 Series’ turning circle is 2 feet tighter than the GranTurismo Convertible’s (38.4 feet vs. 40.4 feet).
The BMW 6 Series may be more efficient, handle and accelerate better because it weighs up to about 350 pounds less than the Maserati GranTurismo Convertible.
The design of the BMW 6 Series amounts to more than styling. The 6 Series has an aerodynamic coefficient of drag of .32 Cd. That is lower than the GranTurismo Convertible (.35) and many sports cars. A more efficient exterior helps keep the interior quieter and helps the 6 Series get better fuel mileage.
The 6 Series Convertible has a much larger trunk with its top down than the GranTurismo Convertible (10.6 vs. 6.1 cubic feet).
Unlike the driver-only memory seat in the GranTurismo Convertible, the 6 Series offers an optional passenger memory, so that when drivers switch, the memory setting adjusts the driver’s seat, steering wheel position, outside mirror angle, climate settings and radio stations and the front passenger seat also adjusts to the new passenger’s preset preferences.
In case of a sudden change of weather, the 6 Series has a standard remote convertible top which can be raised from a distance to protect the interior of the vehicle from damage. The GranTurismo Convertible doesn’t offer a remote top, so the driver will have to run to the car, get in, turn the ignition on and raise the top to prevent the interior from being damaged.
Heated windshield washer nozzles are standard on the 6 Series to prevent washer fluid and nozzles from freezing and help continue to keep the windshield clear in sub-freezing temperatures. The GranTurismo Convertible doesn’t offer heated windshield washer nozzles.
While driving with high beams on, sensitive light sensors available for the 6 Series detect other vehicles which could be blinded and automatically switch to low beams. The GranTurismo Convertible doesn’t offer automatic dimming high beams.
When the 6 Series is put in reverse, the passenger rearview mirror tilts from its original position. This gives the driver a better view of the curb during parallel parking maneuvers. Shifting out of reverse puts the mirror into its original position. The GranTurismo Convertible’s mirror doesn’t automatically adjust for backing.
The 6 Series’ optional air conditioned front seats cool the driver and front passenger and help take the sting out of hot leather in Summer. The GranTurismo Convertible doesn’t offer air conditioned front seats.
To keep a safe, consistent following distance, the 6 Series Automatic offers an optional Active Cruise Control, which alters the speed of the vehicle without driver intervention. This allows the driver to use cruise control more safely without constantly having to disengage it when approaching slower traffic. The GranTurismo Convertible doesn’t offer an adaptive cruise control.
The 6 Series’ standard steering wheel mounted cruise control is close at hand. The GranTurismo Convertible’s standard cruise control is on an over-crowded turn signal stalk.
Optional BMW Apps for the 6 Series allows the driver and passengers access to select programs on their smartphones, including reading text messages aloud, playing internet radio stations, tagging songs to buy them later, following twitter accounts and other online activities without taking their eyes off the road or their hands from the wheel. The GranTurismo Convertible doesn’t offer factory integrated smartphone program access.
The 6 Series’ standard GPS navigation system has a real-time traffic update feature that offers alternative routes to automatically bypass traffic problems. (Service available in a limited number of metro areas.) The GranTurismo Convertible’s navigation system doesn’t offer real-time traffic updates.
The 6 Series’ optional Parking Assistant can parallel park or back into a parking spot by itself, with the driver only controlling speed with the brake pedal. The GranTurismo Convertible doesn’t offer an automated parking system.