Automotive Engineer

While there is a growing demand in Europe for low-cost vehicles, most consumers want more for their money, not less. This is making the C-segment a tough place to do business.

For the mainstream carmakers, this has meant adopting premium cabin materials, boosting performance, and offering higher levels of ride and handling. For premium OEMs, it has meant entering a segment where they have not traditionally been present and taking on brands with much more experience in building compact cars.

On top of that, seamless connectivity of electronic devices with the vehicle is now an expectation of consumers. So are the latest advanced driver-assistance systems, active safety features, and low emissions.

Finding the solutions to these often conflicting targets is one of the things that makes vehicle engineering so challenging, but also rewarding. This was the experience of the team responsible for the third-generation Mercedes-Benz A-Class.

“It’s much more rewarding – definitely,” says Dr Jörg Prigl, Daimler’s vice-president of programme management for compact cars. “Consumers’ expectations are changing. If you go back five or six years customers in this segment were buying cars just for price reasons but now people are downsizing, and they are going to expect systems they never had before.

“These cars are getting as complex as the E-Class, and this is a challenge because of the price sensitivity in this segment. And everything has to fit in a very small space.”

The starting point for development of the A-Class was a new vehicle architecture. Before there was just the A- and the B-Class, but, as well as the replacements for those models, Daimler planned for another three, including a compact coupe. Five vehicle lines from one architecture means a lot of commonality in modules and components, and only works if all the key parameters are clearly defined from the outset. It’s not easy, says Prigl, and meant starting with all five concepts in mind: not just designing the B-Class first, then the A-Class and worrying about the other models later. “You have to know the common package and common dimensions for all five cars,” he says. “You choose the best compromise and then you have the wheelbase, width, where the firewall is and where the engine compartment is.

“These are the basics for the architecture and around this you can shape a car with a high seating position, a low seating position, an SUV or whatever you want – if you keep this stable. If you don’t keep this stable you fail.”

It helped that, in parallel with the architecture, the engines, transmissions and chassis modules were also designed from scratch. This improved packaging, because mounting points could be optimised, and also vehicle dynamics: competition is intense from other premium cars, such as the BMW 1 Series, and from mainstream models such as the Ford Focus. 

So engineers from Daimler’s AMG performance division were involved in development and helped to define chassis geometry, hardware and tuning parameters – for the mainstream versions as well as for the forthcoming AMG A45 all-wheel drive variant. “They gave us some of the components on the front axle they developed for the AMG car,” says Prigl.

Fuel efficiency was another important development target. Features such as rack-mounted electric power steering help to reduce fuel consumption, but a lot of work went into improving the fundamental issues of aerodynamics and vehicle weight.