The new BMW 5-series and Mercedes E-class have been pitted together in an exclusive head-to-head test in this week's Autocar magazine.
For 23 years, every iteration of the 5-series that has gone up against the E-class has come out on top, but this time tester Andrew Frankel was confident the Five faced the hardest fight of its life.
The current E-class is at the top of the game, having pasted the outgoing 5-series in a previous test, and dusted the Jaguar XF.
The test pits the 3.0-litre diesel engined Merc - the best on offer, we think - against the 530d, historically the best of the bunch.
Exterior and interior styling
Both cars look disappointing, notes Frankel. The Mercedes is odd, the BMW just bland and unimaginative.
Inside the 530d BMW has made useful progress, and whether its cabin is preferable to its rival's depends on your priorities. Certainly it works much better: its switchgear is more lucidly arranged, its dials are clearer, the new iDrive controller clearly superior to Mercedes' rival Command system.
What the BMW interior lacks is a sense of occasion. Less coherent it may be, but the way the E-class deploys its wood and leather and subtle but extensive use of chrome has a class missing from the BMW.
The real news is how close the BMW now comes to offering E-class interior space; the E-class's advantage on leg room has been much reduced. The Five is fractionally smaller all round, but for the first time it can seat four large adults in comfort.
Here, it is a hideously close-run contest, determined by nuances here and there and a presumed order of priority that some customers may not share.
Most importantly, both are fine cars to drive fast or slow, in a straight line or through some bends.
The Merc can't match the BMW engine objectively, because its 0-62mph time of 6.9sec is 0.6sec off the 530d's benchmark. Instead, it contents itself with being quieter, smoother and, as a result, more sophisticated, while still being plenty swift enough to offer all the performance most buyers will ever want (or indeed use).
The BMW is easier to drive, requiring provocation few will dole out to unsettle it. The Mercedes is more softly sprung and rolls more, offering a little less grip. However, it has better steering and - more surprisingly - it's actually better balanced too.
The E350 CDI certainly offers better ride quality, but no-one with standard suspension on their car is going to return the 5-series complaining the ride is too stiff. Over long distances some owners may prefer the taut feel of the 530d, as well as its better fuel consumption (45.6mpg with auto box v 40.9mpg) and lower CO2 emissions (160g/km v 181g/km).
Even so, the Merc is quieter, especially in town or pressing on down a country road.
The BMW is a more complete car than the old model, and if that means it's lost a little of teh old enthusiasm, some would argue that this is a price worth [paying for its broader base of talents.
But the Mercedes has rediscovered the values of quality, comfort and luxury. The result is two gloriously different cars.
Truth is, buyers will probably choose on which skill set is more appropriate to their desires and circumstances.
But, forced to choose, Frankel goes for the Merc "by a gnat's g-string".
For the full story buy this week's Autocar magazine, on sale now.