The Cascada 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 4 Series Convertible doesn’t offer a whiplash protection system.
Both the Cascada and the 4 Series Convertible 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, available collision warning systems, lane departure warning systems and front parking sensors.
Buick’s powertrain warranty covers the Cascada 2 years and 20,000 miles longer than BMW covers the 4 Series Convertible. Any repair needed on the engine, transmission, axles, joints or driveshafts is fully covered for 6 years or 70,000 miles. Coverage on the 4 Series Convertible ends after only 4 years or 50,000 miles.
There are almost 8 times as many Buick dealers as there are BMW dealers, which makes it much easier should you ever need service under the Cascada’s warranty.
The Buick Cascada’s engine uses a cast iron block for durability, while the 4 Series Convertible’s engines use an aluminum block. Aluminum engine blocks are much more prone to warp and crack at high temperatures than cast iron.
J.D. Power and Associates’ 2015 survey of the owners of three-year-old vehicles provides the long-term dependability statistics that show that Buick vehicles are more reliable than BMW vehicles. J.D. Power ranks Buick second in reliability, above the industry average. With 36 more problems per 100 vehicles, BMW is ranked 18th.
For better traction, the Cascada has larger tires than the 4 Series Convertible (245/40R20 vs. 225/45R18). The Cascada’s tires are larger than the largest tires available on the 4 Series Convertible (245/40R20 vs. 225/40R19).
The Cascada’s tires provide better handling because they have a lower 40 series profile (height to width ratio) that provides a stiffer sidewall than the 4 Series Convertible’s standard 45 series tires.
For better ride, handling and brake cooling the Cascada has standard 20-inch wheels. Smaller 18-inch wheels are standard on the 4 Series Convertible. The 4 Series Convertible’s largest wheels are only 19-inches.
The Cascada has a standard space-saver spare tire so you can replace a flat tire and drive to have the flat repaired or replaced. A spare tire isn’t available on the 4 Series Convertible, it requires you to depend on its run-flat tires, which limits mileage and speed before they are repaired. If a run-flat is damaged beyond repair by a road hazard your vehicle will have to be towed.
For better handling and stability, the track (width between the wheels) on the Cascada is 1.7 inches wider in the front than on the 4 Series Convertible.
The Cascada has a much larger trunk with its top down than the 4 Series Convertible with its top down (9.8 vs. 7.8 cubic feet). The Cascada has a larger trunk with its top up than the 4 Series Convertible with its top up (13.4 vs. 13.1 cubic feet).
Pressing a switch automatically lowers the Cascada’s rear seats, to make changing between passengers and cargo easier. The 4 Series Convertible doesn’t offer automatic folding seats.
The Cascada’s standard folding rear seats are split to accommodate bulky cargo. The 4 Series Convertible’s standard single piece folding rear seat is not as flexible; long cargo and a passenger can’t share the rear seat.
The Cascada has a standard remote vehicle starting system, so the vehicle can be started from inside the driver's house. This allows the driver to comfortably warm up the engine before going out to the vehicle. The climate system will also automatically heat or cool the interior. The 4 Series Convertible doesn’t offer a remote starting system.
To shield the driver and front passenger’s vision over a larger portion of the windshield and side windows, the Cascada has standard extendable sun visors. The 4 Series Convertible doesn’t offer extendable visors.
The Cascada has a standard heated steering wheel to take the chill out of steering on extremely cold Winter days before the car heater warms up. A heated steering wheel costs extra on the 4 Series Convertible.