The 6 Series’ pre-crash front seatbelts will tighten automatically in the event the vehicle detects an impending crash, improving protection against injury significantly. The Cascada doesn’t offer pre-crash pretensioners.
The 6 Series offers optional City Collision Mitigation, which use forward mounted sensors to warn the driver of a possible collision ahead. If the driver doesn’t react and the system determines a collision is imminent, it automatically applies the brakes at full-force in order to reduce the force of the crash or avoid it altogether. The Cascada has a collision warning system without the crash-mitigating brake feature which could reduce stopping distances.
The 6 Series offers all-wheel drive to maximize traction under poor conditions, especially in ice and snow. The Cascada 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 Cascada doesn’t offer a night vision system.
The 6 Series offers an optional Side and Top View Cameras to allow the driver to see objects all around the vehicle on a screen. The Cascada only offers a rear monitor and front and rear parking sensors that beep or flash a light. That doesn’t help with obstacles to the sides.
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 Cascada doesn’t offer a system to reveal objects in the driver’s blind spots.
Both the 6 Series and the Cascada have standard driver and passenger frontal airbags, front side-impact airbags, driver and front passenger knee airbags, side-impact head airbags, front seatbelt pretensioners, plastic fuel tanks, four-wheel antilock brakes, traction control, electronic stability systems to prevent skidding, daytime running lights, rearview cameras and available lane departure warning systems.
The 6 Series’ corrosion warranty is 6 years and unlimited miles longer than the Cascada’s (12/unlimited vs. 6/100,000).
BMW pays for scheduled maintenance on the 6 Series for 2 years and 26000 miles longer than Buick pays for maintenance for the Cascada (4/50,000 vs. 2/24,000).
To reliably power the ignition and other systems and to recharge the battery, the 6 Series has a standard 210-amp alternator. The Cascada’s 140-amp alternator isn’t as powerful.
To reliably start during all conditions and help handle large electrical loads, the 6 Series has a standard 900-amp battery. The Cascada’s 801-amp battery isn’t as powerful.
The battery on the 6 Series is in the trunk, which protects it from hot underhood temperatures which can degrade battery life. By keeping the 6 Series’ battery 20 to 30 degrees cooler, its life is increased by years. The Cascada’s battery is in the hot engine compartment.
J.D. Power and Associates’ 2015 Initial Quality Study of new car owners surveyed provide the statistics that show that BMW vehicles are better in initial quality than Buick vehicles. J.D. Power ranks BMW 6th in initial quality, above the industry average. With 6 more problems per 100 vehicles, Buick is ranked 11th.
The 640i’s standard 3.0 turbo 6 cyl. produces 115 more horsepower (315 vs. 200) and 109 lbs.-ft. more torque (330 vs. 221) than the Cascada’s 1.6 turbo 4 cyl. The 650i’s standard 4.4 turbo V8 produces 245 more horsepower (445 vs. 200) and 259 lbs.-ft. more torque (480 vs. 221) than the Cascada’s 1.6 turbo 4 cyl. The M6’s standard 4.4 turbo V8 produces 352 more horsepower (552 vs. 200) and 281 lbs.-ft. more torque (502 vs. 221) than the Cascada’s 1.6 turbo 4 cyl. The M6 Competition Package’s standard 4.4 turbo V8 produces 392 more horsepower (592 vs. 200) and 279 lbs.-ft. more torque (500 vs. 221) than the Cascada’s 1.6 turbo 4 cyl.
On the EPA test cycle the 640i Convertible RWD gets better fuel mileage than the Cascada (20 city/31 hwy vs. 20 city/27 hwy).
Regenerative brakes improve the 6 Series’ fuel efficiency by converting inertia back into energy instead of wasting it. The Cascada doesn’t offer a regenerative braking system.
In heavy traffic or at stoplights the 6 Series’ 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 Cascada doesn’t offer an automatic engine start/stop system.
The 6 Series’ standard fuel tank has 4.2 gallons more fuel capacity than the Cascada (18.5 vs. 14.3 gallons), for longer range between fill-ups. The 6 Series M6’s standard fuel tank has 6.8 gallons more fuel capacity than the Cascada (21.1 vs. 14.3 gallons).
For better stopping power the 6 Series’ brake rotors are larger than those on the Cascada:
M6 Carbon Brakes
The 6 Series’ standard front and rear disc brakes are vented to help dissipate heat for shorter stops with less fading. The rear discs on the Cascada are solid, not vented.
For better traction, the M6’s tires are larger than the largest tires available on the Cascada (F:265/40R19 & R:295/35R19 vs. 245/40R20).
The 6 Series’ optional 245/35R20 front and 275/30R20 rear tires provide better handling because they have a lower 35 series front and 30 series rear profile (height to width ratio) that provides a stiffer sidewall than the Cascada’s 40 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 Cascada doesn’t offer run-flat tires.
For superior ride and handling, the BMW 6 Series has fully independent front and rear suspensions. An independent suspension allows the wheels to follow the road at the best angle for gripping the pavement, without compromising ride comfort. The Buick Cascada has a rear torsion beam axle, with a semi-independent rear suspension.
The 6 Series has standard front and rear stabilizer bars, which help keep the 6 Series flat and controlled during cornering. The Cascada’s suspension doesn’t offer a rear stabilizer bar.
The 6 Series offers an available active suspension system, which counteracts cornering forces actively, limiting body roll and improving handling and stability. Buick doesn’t offer an active suspension on the Cascada.
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 Cascada’s suspension doesn’t offer adjustable shock absorbers.
For a smoother ride and more stable handling, the M6’s wheelbase is 6.1 inches longer than on the Cascada (112.2 inches vs. 106.1 inches).
For better handling and stability, the average track (width between the wheels) on the 6 Series is 1.1 inches wider in the front and 2 inches wider in the rear than the track on the Cascada.
The 6 Series Convertible has 6 cubic feet more passenger volume than the Cascada (88 vs. 82).
The 6 Series Convertible has a larger trunk with its top down than the Cascada with its top down (10.6 vs. 9.8 cubic feet).
With its coupe or convertible body style, valet key and remote trunk release lockout, the 6 Series offers cargo security. The Cascada’s non-lockable remote release defeats cargo security.
A standard locking center console (which can’t be accessed with the valet key) keeps your small valuables safer in the 6 Series. The Cascada doesn’t offer locking storage for small valuables.
When two different drivers share the 6 Series, the memory system makes it convenient for both. Each setting activates different, customized memories for the driver’s seat (memory seat optional for the front passenger), steering wheel position, outside mirror angle, climate settings and radio stations. The Cascada doesn’t offer a memory system.
The 6 Series’ standard easy entry system raises the steering wheel, making it easier for the driver to get in and out. The Cascada doesn’t offer an easy entry system.
The 6 Series offers an optional heads-up display which projects speed and other key instrumentation readouts in front of the driver’s line of sight, allowing drivers to view information without diverting their eyes from the road. The Cascada doesn’t offer a heads-up display.
If the windows are left down on the 6 Series the driver can raise them all using the key in the outside lock cylinder. On a hot day the driver can lower the windows from outside the vehicle using the key in the outside lock cylinder or the keyless remote. The driver of the Cascada can only raise the windows from inside the vehicle, with the ignition on.
Comfort Access standard on the 6 Series allows you to unlock the driver’s door, trunk and start the engine all without removing a key from pocket or purse. This eliminates searching for keys before loading groceries, getting in the vehicle in bad weather or making a hurried start to your trip. The Buick Cascada doesn’t offer an advanced key system.
The 6 Series’ rain-sensitive wipers adjust their speed and turn on and off automatically based on the amount of rainfall on the windshield. This allows the driver to concentrate on driving without constantly adjusting the wipers. The Cascada’s standard manually variable intermittent wipers have to be constantly adjusted.
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 Cascada doesn’t offer heated windshield washer nozzles.
In poor weather, headlights can lose their effectiveness as grime builds up on their lenses. This can reduce visibility without the driver realizing. The 6 Series has standard headlight washers to keep headlight output high. The Cascada doesn’t offer headlight washers.
While driving with high beams on, sensitive light sensors standard on the 6 Series detect other vehicles which could be blinded and automatically switch to low beams. The Cascada 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 Cascada’s mirror doesn’t automatically adjust for backing.
The 6 Series has standard automatic dimming rear and side view mirrors which automatically darken quickly when headlights shine on them, keeping following vehicles from blinding or distracting the driver. The Cascada has an automatic rear view mirror, but its side mirrors don’t dim.
Optional air conditioned seats in the 6 Series keep the driver and front passenger comfortable and take the sting out of hot seats in Summer. The Cascada doesn’t offer air conditioned seats.
The 6 Series has a standard center folding armrest for the rear passengers. A center armrest helps make rear passengers more comfortable. The Cascada doesn’t offer a rear seat center armrest.
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 Cascada doesn’t offer an adaptive cruise control.
The 6 Series (except xDrive)’s 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 Cascada doesn’t offer an automated parking system.