Mercedes-Benz engineers’ obsession with detail includes making sure the navigation system mapping is correct when undertaking test drives.

So, every road in the navigation system is checked out?

“Why wouldn’t you?” responds Johannes Reifenrath, director of marketing strategy and portfolio and powertrain strategy for the automaker.

“We pay suppliers a lot of money for these systems so we want to make sure they are accurate. If they are not, it is us the customer complains to, not the supplier.”

Checking out the sat-nav is not a specific job, however. Reifenrath said the new E-class had undergone about 36m km (about 23m miles) of testing, so the engineers thought they might as well make the most of that amount of time on the road.

Some of the new E-class development was carried out on British roads with prototypes assessed by “myriad drivers” with feedback and final adjustments made if necessary. Test drivers included experts and ‘normal’ Mercedes-Benz UK staff.

Gadgets include front seat side bolsters that automatically add additional support to keep the occupant firmly in place as a corner tightens.

High beam headlights ‘look’ around corners, automatically dip for oncoming traffic and the steering wheel pulses to warn of the presence of an as yet unseen pedestrian.

That same steering wheel rim-vibrating ‘stick shaker’ [similar technology is used in aircraft to warn pilots of an impending stall] will let you know if the car veers out of its lane and the blind spot indicator warns if another vehicle is overtaking. Brake-assist radar helps prevent rear-end collisions.

Like some versions of GM Europe’s new Opel/Vauxhall Insignia, the latest E-class can also work out what the road speed limit is (although this will not be immediately available here in the UK as it only recognises European signs so far).

An audible warning and a coffee cup symbol appear on the instrument panel when the car thinks it’s time the driver took a break, too.

This E-class model line, under various names, dates back 60 years and is now in its ninth generation. The E-class name has been used since the mid-80s and some 70,000 have been sold in the UK where it continues to shift at a rate of around 10,000 a year, slightly below the BMW 5 series and comfortably above the Audi A6.

The E-class of ’09 has Mercedes’ latest generation ‘Blueefficiency’ diesel and petrol engines with reduced fuel consumption and lower CO2 emissions.

These models come with newly-developed tyres with up to 17% less rolling resistance, plus energy saving alternators, fuel pumps, air conditioning and power-steering pumps which all switch off when not in use.

A stop-start system comes with the E200 CGI manual which will be introduced in late summer. Further down the line, Reifenrath said, diesel-electric hybrid models will be introduced in 2011.

Mercedes’ E-class product manager for the UK, Nick Williams, said diesel versions account for 87% of sales here while 95% of total volume has automatic transmission.

Corporate sales have increased 16% over the past two years and small fleet sales are a key target in 2009.

The UK range has been reduced from five to three trim levels: SE, Avantgarde and Sport with the full  range being phased in between June and September.