In terms of occupant protection, size doesn't matter. Volvo safety engineers were challenged in many ways by the compact S40 sedan and V50 wagon. The goal was always to make the all-new S40 and the new V50 as safe for occupants as is the larger S80 sedan; the challenging goal was accomplished thanks to:

• New, patented front architecture
• Four different grades of steel
• Clever engine compartment packing
• Re-engineered collapsible steering column

"When we designed the all-new Volvo S40 and V50, we needed to answer two questions," says Volvo Car's safety engineer Ragnar Crona: "How do we handle the high impact forces from larger vehicles? Where in the compact sedan do we find the crumple zone necessary to provide a "soft" stop for the occupants in the S40 or V50?"

The front structure should deform under high impact force; however, there is a dilemma. This force must be lower than the maximum that the safety cage surrounding the occupants can handle. This translates to mean that collision performance is highly dependent on just how strong the safety cage can be made.

In a traditional front structure, incoming impact forces are transferred from the side members down to the sill and the floor. During this transfer of the impact force, large bending moments are created. These bending moments limit the maximum force that the side member can be designed to withstand.

Therefore, in order not to crush the back-up structure, the force in the side members has to be kept relatively low. The energy that the side member can absorb is a function of how long it is and the force level it can handle. Low force capability gives a long side member - creating an additional challenge when designing a smaller car.

New, patented front architecture
S40 and V50 have a new front architecture for which Volvo has the patent. In S40 and in V50, the forces from the deforming side members are transferred into a web of longitudinal and lateral members that form the front part of the safety cage. This web can be compared to an old-fashioned railroad bridge where zigzag members absorb all forces in the optimum way. With this architecture, we can allow the side members to deform at a higher load. This means that the same amount of energy can be absorbed with shorter side members. The complete front end can therefore be made shorter.

We have used High-Strength Steel in the body area that absorbs the collision energy. This grade of steel is optimal for deformation at a very high load.
In the areas surrounding the occupants, where we want very little or no deformation at all, we have used extra-high-strength steel. This steel grade is very strong but still ductile enough to make sure that the safety cage deforms in a controlled manner.

Each component has a pre-determined parking place
S40 and V50 are thus designed to absorb incoming collision energy and to manage the front-end deformation in a controlled way.

The only potential problem was presented by the rather large five-cylinder engine in the compact S40 and V50 body. "Normally when you design an engine, you make sure that it fits into the car. When we designed the engine for S40 and V50, we made sure it would be slim enough to fit into the engine compartment even after a collision," says Ragnar Crona.

The five-cylinder engine powering S40 and V50 is a newly revised variant of Volvo's five-cylinder inline engine, and it is designed to be extremely slim to allow for the largest possible crumple zone. This new engine gives the occupants more of a survival zone compared to previous Volvo engines.

Everything you find under the bonnet of S40 and V50 has a predetermined position after a frontal impact, piling up in an organised way ahead of the safety cage surrounding the vehicle's occupants.

More space inside
We have also increased the space inside the car during an impact. In a crash, S40 and V50 steering column will collapse more than in previous models. This allows the driver to move further forward inside the car during the crash without compromising safety. As a result, the belt and airbag are better able to help limit the forces imposed on the driver, thus bringing his or her body to a "softer" stop.

Compact car safety
The patented front structure, the engine bay packaging, the combination of different-grade steel and the re-engineered collapsible steering column give the Volvo S40 and V50 a remarkably good front crumple zone. In fact, in terms of frontal collision protection, this clever engineering puts the new compact Volvo sedan and wagon on a par with the current Volvo S80, recognised worldwide as one of the safest cars on the market. It is not possible to change the laws of physics, but new technologies can certainly be harnessed to make compact cars even safer.

Volvo safety engineers challenge the laws of physics
"While we cannot change the laws of physics, our aim of building cars that are the safest in their class applies to all models, irrespective of size," says Ingrid Skogsmo, head of the Volvo Car Safety Centre.

• Developed and tested in the world's most advanced safety centre
• New, patented frontal structure with several crumple zones
• Four steel grades interact for optimal deformation
• The same side-impact protection system as in larger Volvo models
• Frontal design with integrated protection for other road users
• 68 percent greater torsional rigidity for all-new S40 compared to current S40
• 34 percent greater torsional rigidity for new V50 compared to current V40
• Unique intelligent driver information system - IDIS
• High level of theft protection

S40 and V50, despite their compact size, offer extremely high safety levels - both protective and preventative. Volvo's primary objective has been reached; that is to engineer the compact S40 and V50 to the same high safety level achieved in the current S80 model.

This is possible for several reasons, including a very stiff body, a new frontal structure and a new intelligent system for driver information.

The safety systems have been developed and tested in the Volvo Car Safety Centre, the most advanced facility of its kind in the world. About 40 full-scale tests have been performed to help ensure that all the on-board components interact.

Crumple zones that employ different grades of steel
In the development of S40 and V50, the engineers started with the crash safety baseline set by the large S80 - with the aim of reaching the same high level with the new compact body.

In a compact car body, the preconditions for efficient deformation are different to those of a large body. Since the necessary deformation is absorbed within a shorter total distance, the various materials' properties must be exploited to the maximum so as to absorb as much of the incoming energy as possible.

"A tough challenge, one that we approached in an entirely new way," confirms Ingrid Skogsmo.

The frontal body structure was divided into several zones, each with a different task in the deformation process. The outer zones are responsible for most of the deformation. The closer the collision forces get to the passenger compartment, the less the materials used deform. The objective is that the passenger compartment should remain intact in most collisions.

To give each zone the relevant properties, different grades of steel are used in different areas. Four different steel grades are used. In addition to conventional bodywork steel, three different grades of high-strength steel are employed: high strength steel, extra high-strength steel and ultra high-strength steel.

The zonale system enables the collision forces to be absorbed in a highly ingenious and effective manner.

Low-speed deformation zone
The front bumper incorporates an extremely rigid cross-member of boron steel (Ultra High-Strength Steel). The attachments to the longitudinal members of the body are designed in the form of 'crash boxes', which help absorb the forces generated by a low-speed collision without damage to the rest of the body structure. The crash boxes can be replaced easily at reasonable cost.

High-speed deformation zone
The straight sections of the side members are made of High-Strength Steel, a very ductile grade of material, which is optimised for high energy absorption. This is the zone that accounts for most of the deformation in a collision.

In addition, Volvo has opted to include upper side members also in the compact S40 and V50 since they provide significant occupant protection if the vehicle should collide, for example, with a truck platform or a loading pier.

Back-up zone
The section member that turns outward toward the A-post is designed to act as a barrier for the cabin space and as a back-up reducing deformation. The design also helps minimise the risk of a front wheel penetrating the interior. The wheel instead helps absorb the collision forces. This section is extremely rigid and is made of extra high-strength steel.

Three-way attachment
A rigid cross-member connects the A-posts and lower side members. On each side they form an extremely rigid three-way attachment, which very strongly helps to maintain the cabin space in a severe crash. The new front structure is one of Volvo's many patented safety designs.

Compact engines contribute to crash safety
Owing to efficient packaging; the engines in S40 and V50 have been slimmed by 200mm. Since the engines are installed transversely, the reduced width creates greater space between engine and passenger compartment. In a collision, the engine can be pushed no less than 150mm rearwards before the engine block comes into contact with the cross-member near the bulkhead.

S40 and V50 also shares the same type of interior safety systems as found on the S60 and S80 models.

The steering column can be deformed up to 140mm. When deformed, the steering column moves horizontally, to provide the optimal airbag position for this vehicle.

S40 and V50 share many safety features with the S80 model:

• Collapsible pedals
• Dual-stage airbags
• Seat belt pretensioners for the front seats and rear outboard seats
• Force limiter for the front seat belts
• Belt reminder for the front seats and rear seats

Side Impact Protection System
All-new S40 is 50 mm wider than its predecessor, and new V50 is 54mm wider than V40. This additional width creates added space for deformation in a collision. In other respects, S40 and V50 have the same type of side impact protection as found on the S80 Volvo model, with SIPS (Side Impact Protection System), side-impact airbags and IC (inflatable curtains). These curtains are designed to provide enhanced occupant protection in rollover accidents, by deflating more slowly (approximately 3 seconds) than the front airbags.

The side airbags are larger than in the previous S40 and V40 models so as to help provide more effective protection at hip and chest height.

Several features contribute to the stiffer body and help reduce side intrusion:

• Reinforced, transversely installed tubular beam between the A-pillars
• Diagonally installed beams of ultra high-strength steel in the doors
• B-pillars have been significantly reinforced and are dimensioned to provide enhanced protection

S40 and V50 have been designed to provide the highest level of occupant protection in a rear-end collision too. Volvo's system for avoiding neck injuries - WHIPS (Whiplash Protection System) - is one of the most effective on the market. In the event of a severe impact from the rear, the seat backrest and head restraint accompany the movements of the occupant's body.

The seats and backrests are of a particularly robust design. They are dimensioned to withstand high loads from items such as unsecured luggage, while at the same time they are designed to yield in severe crashes where a balance of strength and flexibility is important for occupant safety.

"Our seats are far sturdier than those usually found in the compact segment," says Ingrid Skogsmo.

Protection for other road users
The design of all-new S40 and new V50 front is characterised by clean, smooth surfaces and rounded corners. The curves and panels are shaped to reduce the risk of injury to pedestrians and cyclists in the event of an accident.

Furthermore, the front has an energy-absorbing structure ahead of the bumper so as to help reduce the risk of leg injuries.

The bonnet and front fenders are designed to absorb collision energy. This helps reduce the risk of head injuries. In addition, the compact new petrol engines leave a generous 70mm of free space between the cylinder head and bonnet.

Built for children too
Just like the rest of the Volvo range, the all-new S40 and V50 were developed with a keen focus on children. The body's safety structure and interior safety systems are designed and dimensioned to help protect the youngest occupants too. Both rear outer seats are fitted with integrated child booster cushions for children above three years of age.

Child booster cushions are a standard feature in all S40 and V50 models except T5, where it is offered as a $550 option.

Preventive Safety
The all-new S40 body is 68 percent stiffer than that of its predecessor. The new V50 is 34 percent more torsionally rigid than that of the out-going V40.

This torsional rigidity contributes to stable, predictable and consistent behaviour on the road. The cars' chassis design, with broad track and long wheelbase, also has a positive effect on stability.

• Front track is 1535mm (63mm wider than the previous S40 model).
• Rear track is 1531mm (57mm wider)
• Wheelbase is 2640mm (78mm longer)

The suspension is independent at all four corners, with spring struts at the front and a multi-link system at the rear. The rear suspension provides a certain degree of passive steering to counteract any tendency to skid.

Excellent braking
S40 and V50 have extremely powerful ABS brakes - with electronic brake-force distribution to the rear wheels and automatic panic-braking assistance - EBA (Emergency Brake Assistance). The front wheels feature ventilated discs. The disc size is dependent on engine power and vehicle weight (diameter up to 320mm).

Projector-type headlamps
The headlamps feature projector-type low beams. The concentrated beam of light is surrounded by a "halo" which helps oncoming drivers judge the distance to the car.

Bi-Xenon gas discharge lamps for high and low beam are available as an option ($2250) on all S40 and V50 models except T5 - where Bi-Xenon lamps are standard equipment.

Additional side-mounted turn indicators in the door mirrors and integrated side-marker lights in the front and rear lamps make S40 and V50 easy to see from the side too.

Ergonomic driver's environment
An ergonomically designed seating position with all the instruments and controls in just the right position makes for safer progress. In this respect, S40 and V50 continue a renowned Volvo tradition. It has a comfortable and conveniently operated driver's seat, an adjustable steering wheel and a logically laid out instrument panel.

Steering wheel-mounted controls for the audio system and cruise control add further to driving safety.

Security
Volvo's holistic view of safety encompasses not just protective and preventative safety, but also personal security. S40 and V50 are designed to provide effective protection for occupants and their property, both while on the move and when the car is parked.

The level of theft protection is very high, as a result of close co-operation with Thatcham, the world-leading automotive research and technology centre.

S40 and V50 are equipped with a number of protective functions:

• Electronic immobiliser
• Electronic anti-theft "marking"
• Uniquely identified control modules
• Audio system as an integral part of the on-board electrical system

In addition to this, S40 and V50 have a sophisticated locking system with a wide range of scope for personal settings:

• Unlocking of doors - all doors or only the driver's door
• Automatic locking of the doors after moving off - with an option to cancel
• Indicator blink when unlocking or locking - with an option to cancel
• Variable timing for Follow-Me-Home and Approach Light - 30, 60 or 90 seconds

The remote can also open all windows, i.e. to cool down the interior on a hot day. It will also close the sunroof and all windows.

S40 and V50 can also be equipped with laminated door windows, an unusual feature in a compact car. Laminated glass is extremely difficult to smash and provides enhanced protection against break-ins.