BMW 5 Series ‘clean sheet’

BMW’s new F10 5 Series may be closely associated with the 7 Series and 5 Series GT, but this doesn’t mean it’s simply a modified version of those cars.

‘In terms of driving dynamics, we always start from a clean sheet,’ explained Jos van As. But how, given the interrelation of components? By starting from the start, not working backwards.

Van As talks through the methodology, showing the 5 is more than a scaled down 7 (or, indeed, a 1/6th-price Rolls-Royce Ghost…). His work begins before a CAD pixel is created, through a logical build-up process:

•    DNA – ‘Here, we define proportions, weight distribution, drive concept, aero effects such as lift coefficient front and rear, and so on’
•    Suspension – Spring and damper rates are decided upon (‘ride quality was the focus with F10’)
•    Tyres – Design of car, weight of car under different load conditions (‘for example, we can decide what size wheels we can fit, and what pressures we need’)
•    Steering – Ratio, speed of response (‘the 5 Series has EPAS, like the 7 Series, but the ratio is faster’)

Once you have all this, you can begin setting up the standard suspension. With the 5 Series, says van As, ‘a team of 4 engineers set up the standard car.

‘This standard car is the base; we add on dynamic features to this platform, all controlled by ICM.’

As yet, then, there are no specific ‘sport’ suspensions for the 5 Series, but more dynamic variations of the standard car, created through technological add-ons. That’s what you can achieve with electronic dampers and adaptive anti-roll, ‘all controlled by ICM’.

Sounds like a cop-out? Not at all, such is the advanced level of ICM. ‘It’s all interconnected, all systems are parameticised. The chassis alone has 45,000 parameters – so it is quite hard work to get it right!’

Here’s where a strong, stiff body-in-white becomes vital, says van As. ‘It is important we get a good structure so we can discover how one change interacts with another.’

While those high-end cars could indeed have a fair few suspension settings, ‘the customer does not need 45,000 (!), so they get 4. ‘

‘These characterise the car in 4 different ways – making 4 cars in 1 from a dynamic point of view.’

Shrunken 7 Series, then? No – it’s a fair bit more than that…

Secrets of the BMW 5 Series

BMW drive back advice

BMW Z4 has 3 Series Convertible to thank