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2018 4 Series Convertible

The BMW 4 Series Convertible is a topless, high-style alternative to the 3 Series sedan. Also offered as a coupe, it is quieter, cushier and more tech-focused than its predecessor but it continues to serve up an engaging driving experience to go along with its distinctive look.


In years past, the 3 Series' coupe companion was known for conservative, understated styling, but the 4 Series breaks with tradition by wearing highly evocative sheet metal.

Its wide stance is accentuated up front by a muscular hood, a flared lower fascia, and BMW's fused grille/headlight design. In other words: it looks a lot like a 3 Series. The flanks feature sharply creased character lines and vent-like Air Breathers that reduce turbulence in the front wheels.

The 4 is fitted with a three-piece retractable hard top that electronically opens or closes in 20 seconds at speeds of up to 11 mph. The hard top provides a quieter ride and better all-weather insulation than a conventional fabric top while giving the convertible a coupe-like silhouette when closed.

The 4 Series is fitted with a lowered, specially tuned version of the 3 Series sedan's suspension. A strut located between the front axle's sub-frame unit and the body stiffens the front end for more precise steering and better body control, while the rear five-link suspension is also optimized for spirited driving. Note the electronically-assisted steering is less communicative than the hydraulic setup of the 4's predecessor.

Life aboard

Inside, the 4 Series' dashboard is largely identical to that of the 3 Series. That means there's simple, straightforward instrumentation, driver-focused controls, and premium materials.

Mounted front and center is a 6.5-inch infotainment screen that displays sound system, climate control and (when equipped) navigation system info. It's controlled by BMW's much-improved iDrive interface, although redundant buttons and voice commands give users alternate means of accessing the electronics.

Despite its attractive styling, the 4 Series boasts a reasonably spacious backseat that can hold two adults for around-town journeys. The rear backrest folds down in 40:20:40 segments for added utility, and when the center section is folded, it acts as a ski or snowboard slot.

Technical specifications

The 4 Series line-up includes two models named 430i and 440i, respectively.

The 430i's 2.0-liter turbocharged four-cylinder engine makes 248 horsepower at 5,200 rpm and 258 pound-feet of torque from 1,450 to 4,800 rpm. It accelerates from zero to 60 mph in six seconds flat in its fastest configuration.

The 440i benefits from a turbocharged 3.0-liter straight-six that delivers 320 horsepower at 5,500 rpm and 330 pound-feet of torque between 1,380 and 5,000 rpm. Its zero-to-60-mph time checks in at 5.1 seconds.

The 4 Series Convertible is automatic-only. Rear-wheel drive comes standard regardless of how many cylinders are under the hood, and BMW's xDrive all-wheel drive system is offered at an extra cost.

The 430i returns up to 24 mpg in the city, 34 mpg on the highway, and 27 mpg in a combined cycle. Opt for the 440i and you'll see those figures drop to 21, 29, and 24, respectively.

Standard and optional equipment

The 430i comes standard with a multi-function steering wheel, navigation, SensaTec upholstery, 18-inch alloy wheels wrapped by run-flat tires, a universal garage door opener, auto-dimming mirrors, rain-sensing wipers, automatic LED headlights, LED fog lights, automatic climate control, and Bluetooth connectivity.

The 440i adds, in addition to the bigger engine, a Nappa leather-upholstered steering wheel, keyless entry, and a surround-sound system.

The list of extra-cost options includes metallic paint, leather upholstery, a heated steering wheel, 19-inch alloys, an adaptive M suspension, a heated steering wheel, a digital instrument cluster, wireless charging, a head-up display, and adaptive cruise control. There are also numerous option packages that make the 4 sportier, more luxurious, or both.

Occupant safety

All 4 Series models come standard with dual front, front knee, and front side in addition to traction and stability control systems and a tire pressure monitoring system.

Key competitors

4 Series buyers can also look at the topless variants of the Mercedes-Benz C-Class and the Audi A5.