safety in design
When you are on the leading edge of vehicle efficiency and small vehicle design, the issue of safety is a critical element. That's why the core design philosophy of the smart fortwo is focused on something called the tridion safety cell. Much like a nut is protected by its hard outside shell, the smart fortwo's occupants are protected by a steel housing that combines longitudinal and transverse members that displace impact forces over a large area of the car. So it's not about the amount of steel, but how that material will resist an impact. That's what the tridion safety cell is all about.
what's a crash box?
The smart fortwo is designed with steel bumpers at the front and rear that are bolted to the safety cell's longitudinal beams via slip tubes. They can be replaced after minor collisions at low costs. For parking lot bumps, an impact of less than 2 miles an hour won't affect the crash box at all. Up to about 10 miles per hour, the slip tubes move to keep impact away from the tridion safety cell. Over 10 miles an hour, the tridion safety cell transmits impact over its entire surface to dissipate energy and protect its occupants (assuming a perpendicular impact involving the entire front width). At the rear of the car, the crash box is also built of steel, which crumples much like the front slip tubes do. At an impact exceeding the severity threshold, the fuel supply to the engine is stopped and the central locking system is automatically unlocked.
side impact strength
You might have noticed that the smart fortwo has a pretty short wheelbase, but you probably haven't thought of that as a safety feature. If you suffer a side impact in your smart fortwo, chances are that the car hitting you will hit the wheels and tires of your car. Those wheels and tires are connected to either longitudinal structural members or axles that help to displace the crash energy. Each door also has a side brace installed.
active safety system
The smart fortwo comes standard with many active safety features that will introduce you to a whole new set of acronyms and keep you safer in the process.
esp® - One of the standard features on your smart fortwo is something called Electronic Stability Program or esp®. When the esp® sensors indicate a skid or swerving of your car, they automatically control the engine throttle and the Anti-Lock brakes to maintain your present course. Also integral to the esp® safety system is Electronic Brake-Force Distribution Control (EBD), which helps to prevent the rear wheels from over-braking.
ABS - A feature of esp®, Anti-Lock Brake Systems (ABS) will apply and release each brake independently to keep you from skidding regardless of the type of road surface each wheel is on.
CBC - When you enter a corner and apply your brakes, the unequal forces at each wheel can result in a skid or a complete "end-around." With Cornering Brake Control (CBC) the inner wheels require less brake force due to less traction. CBC counteracts a potential tendency to swerve by distributing brake forces selectively - even below the threshold of ABS activity.
HBA - Avoiding accidents is often measured in inches. Hydraulic Brake Assist (HBA) is standard on the smart fortwo. Apply the brakes in a dangerous situation and the hydraulic brake assist helps initiate controlled emergency braking.
ASC and ETC - Acceleration Skid Control (ASC) and Engine Torque Control (ETC) are designed to help the smart fortwo move forward on slippery surfaces. ASC acts much like a differential lock but does it by directing power to the wheel offering optimum traction. ETC provides engine control when driving on slippery surfaces. It "feathers" the throttle on low traction acceleration and limits torque in down shifting applications.
HSA - The smart-shift Transmission® of the smart fortwo is equipped with Hill Start Assist (HSA) which allows you to pull away on a hill without having to apply the handbrake. As you lift your foot from the brake pedal while stopped on a hill, HSA holds the brakes for about a second to give you time to move your foot to the accelerator.
passive safety system
All smart fortwos are equipped with a package of passive safety features. Full driver and passenger front, side, window* and knee airbags for head, thorax and leg protection come standard. The steering column will collapse in the event of a serious front-end collision.
The smart fortwo also has a sophisticated safety belt system, incorporating belt tensioners that sense motion changes to reduce slack in a few milliseconds while also triggering a belt force limiter designed to release a controlled amount of pressure on the chest before the pressure becomes too great. In addition, the seats are designed with a strong modular steel structure with integrated headrests.
*Window airbag not available on the Passion Cabriolet.
