Pay attention to these key repair areas when repairing a Smart Car

Smart Car subcompacts Makrolon crumple zones door frames cooling modules impacts bars Subcompacts (passenger cars with 85 to 99 cubic feet of interior volume) have been around for many years, gaining and losing popularity based on gas prices. Modern subcompacts include the BMW mini, Chevy Aveo, Toyota Yaris and the Honda Fit. Although these vehicles all have some specific repair methodology, fixing one actually is pretty straightforward. That may not be the case with newer subcompacts and new breed of super minis, or city cars as they are known in Europe, that are finding their way into garages over here. Some of these cars are unique, such as the Mercedes Smart Car. If you look around, you will see quite a few of these vehicles on the road today.

Subcompacts, like any other vehicle, are built with safety in mind. The Smart Car for two (a two-seater) is equipped with driver and passenger front airbags, side-impact airbags and a collapsible steering column. It also has a sophisticated seatbelt system, incorporating belt pre-tensioners and a belt force limiter, designed to exert a controlled amount of pressure on the occupant's chest while an impact is occurring.

Additionally, the seats are a modular steel construction with headrests integrated into the seat itself (see Fig. 1). The 2008 version of this model earned the highest available ratings from the Insurance Institute for Highway Safety for front- and side-impact crashworthiness. The Smart Car offers safety, efficiency and, for repairers, some repair challenges due to its unique design. Here's some key areas you'll want to pay special attention to when this vehicle visits your shop.

Step 1: Identify materials

The Smart Car's lightweight roof material actually is a module made of Makrolon, a polycarbonate plastic from Bayer Material Science, specifically designed for use in automotive glazing applications (see Fig. 2). Covering an area of about 1.2 square meters, it is to date the largest polycarbonate roof module in a production vehicle anywhere in the world.

The front mounting panel is a composite bolt-on panel. It acts as a headlamp-mounting panel/core support. In a fairly severe front impact, this panel would probably sustain enough damage to warrant replacement. Like most plastic core supports, only minor damage should be considered as repairable.

Doors are designed to bounce back from the abuse they will take in space-starved urban environments. The door skin is a flexible poly material, similar to Saturn's plastic panels. It's very forgiving and will absorb most minor parking lot dings.

Step 2: Examine crumple zones and areas designed for strength

Note the rail extensions in Fig. 3. These are bolt-on and are manufactured with convolutions, designed to crush during impact. They likely will save frame rail damage under certain impact conditions. They will need to be examined closely in the event of a front-end collision.

Refer to the cutaway view of the windshield pillar in Fig. 4 and particularly the design of the inner portion of the pillar. It is engineered with a rounded re-enforcing member (in red), which adds tremendous strength to the panel when assembled. Repairing damage in this area might present some challenges because of this design. Obviously, fixing a kink in the outer panel may leave the inner panel damaged and weak, causing a possible safety issue later.

One of the most interesting subassemblies on this vehicle is the door. The doorframe is very rigid, with the hinges integrated into the doorframe and intrusion beam (see Fig. 5).

Doors frames need special attention. Because the skin is flexible, in the event of an impact to the door, special attention should be paid to the frame and hinge area. Removal of the outer skin and careful inspection of the doorframe itself is highly recommended.

Kinks or cracks would likely result in the replacement of the frame assembly. The entire side of the vehicle is basically the door and door aperture, which adds strength. There is a body side and a door side to the hinge assembly, connected by a pin and bushing. There are some very minor adjustments for door alignment that can be made in this area if they are needed.

Step 3: Mind the rear end

The engine of the Smart Car is rear-mounted, making this an area of particular interest in a rear-end collision. The cooling modules are not located in the rear of the vehicle, so impacts to the rear or drivetrain area of the vehicle won't cause coolant leak issues. The engine cradle is fairly large for a vehicle this small because it serves several roles. It adds rigidity to the entire rear area of the vehicle and acts as a platform for all the mechanical and suspension components. It also is modular and is fairly easy to remove and adds in vehicle stability and handling.

The rear bumper cover is made in sections. The center is a small cover over the rear bar itself, while the right and left rear covers are huge and actually look more like the quarter panels rather than the bumper cover. These are made of a rubber-like material and are repairable using standard plastic repair techniques.

The tail lamps also are mounted in this area. The rear impact bar is equipped with extensions that are convoluted. These, like the front, are designed to crush in a rear impact.

Final word: It's a small world

Since larger, less fuel efficient vehicles probably will continue to disappear, smaller more fuel efficient cars will likely begin to make up a larger segment of the vehicles on the road in the future. It is inevitable that your shop will begin to see more and more of these types of cars.

As demand increases, new technologies will emerge. I suggest you make sure you are prepared and make it a point to allocate time and resources for the training needed to fix these types of vehicles. They aren't just visiting. You can bet they're here to stay.