We pit two diesel-powered German luxury sedans against each other to find out which mixes performance and economy the 535d: from $121,900 plus on-road costs. six-cylinder turbo diesel; 230kW/630Nm; eight-speed auto; RWD Audi A6 Biturbo: from $119,700 plus on-road costs. V6 turbo diesel; 230kW/650Nm; eight-speed auto; AWD Value BMW Looks like it starts a little behind the eight-ball by carrying a $2200 premium over the Audi but recently-facelifted model adds more equipment than its predecessor including LED headlamps, hands-free opening for the boot and new safety systems such as lane departure, forward collision and pedestrian warning as well autonomous braking in city traffic. New additions aside, the 535d has a long list of luxury gear such as leather trim, power seats, dual-zone climate control and a comprehensive suite of functions within its colour display including sat nav, Bluetooth phone and audio streaming, internet connectivity, digital radio and top-shelf Harman Kardon audio. Audi German brand has updated the Biturbo for MY14, adding 19-inch alloy wheels and four-zone climate control – no doubt a strategic move to keep it in-line with the BMW 535d. It almost matches the BMW for almost everything else when ordered with the optional Technik Package that includes lane-keeping assistance, 360-degree camera, digital radio and LED headlights. But it costs an additional $3000. Winner: BMW Inside BMW The cabin has a classy yet simple layout that fits in well with a lot of its new high-tech features, including a larger infotainment display and a digital instrument panel that changes colour between the driving modes. The rotary iDrive controller that accesses the functions now has a touch pad on top and there’s a new three-spoke steering wheel, which looks a feels sportier than before. Buyers can opt for either the Modern (Pearl Dark inserts) or Luxury Line (Fine Wood inserts) interior trims. The seats are comfortable and there’s decent space for five adults and a generous boot. Audi Doesn’t have the same high-tech instruments and has a smaller multimedia screen that rises from the middle of the dashboard, but does have a more contemporary design with a brilliant mix of materials and faultless quality. Seats could have more lateral support to befit its semi-sporty nature, but otherwise has a slightly more harmonious ambience and a little more rear seat space. Winner: Audi Engine Sweet in-line six cylinder turbo diesel revs cleanly and with plenty of immediate shove. Although it has marginally less torque than the Audi – and it’s available over a slightly smaller powerband – it feels more linear in its delivery. It is well matched to the silky eight-speed automatic with barely perceptible gear changes and is quieter under hard acceleration. The end result is the BMW not as quick as the A6, with a claimed 0-100km/h time of but the trade-off is that is more efficient with combined fuel economy of Audi If you’re after a more visceral experience, then the A6 behaves more like a muscle car. Its surge of pulling power feels as though it comes on stronger when the turbos hit their straps and it has a gruff exhaust when they do. Uses the same eight-speed auto as the BMW to great effect, but with the added traction of its all-wheel drive transmission is slightly quicker to triple figures with Audi claiming it can get there in just Uses slightly more fuel though at Winner: BMW How it Drives BMW Has a more subdued character about it than the Audi, with more a natural feeling to the way its steers, a smoother power delivery and quieter engine note. The adaptive suspension also has a nice blend of comfort and sportiness between its three modes. Audi Its slightly more abrupt performance aside, the A6 feels every bit as luxurious to drive as the 535d. In its default settings, the steering is a bit too light and, being all-wheel drive, there’s less feedback delivered to the driver when pushed hard, but the driver can individually tailor the suspension, steering and gearbox settings to suit their tastes and when you find the sweet spot, it can be either as comfortable or as enjoyable as the BMW. Winner: BMW Options BMW Buyers can easily add tens of thousands of dollars to the purchase price in customising the 535d as BMW has an extensive list of options, including a multitude of alloy wheels to choose from, different leather trims, a $4000 M Sport package with stiffer suspension and unique bumpers, night vision, radar cruise control and adaptive suspension with active roll bars. The most expensive is a high-grade 1200w Bang and Olufsen audio system that costs an extra $9750. Audi Also has an extensive list of costly options that mostly mirrors those available on the BMW as well as some of the features that are standard on its rival, including LED headlamps. Does have larger 20-inch alloys that look great and fill its wheel arches better, but similar-spec B&O audio costs $1000 more. Audi has made it easier for buyers with two bundled packages; the $6500 S Line Sport which adds sports seats, brushed alloy interior inlays, sports steering wheel and suspension settings with the 20-inch alloys, and the previously mentioned Technik Package. Winner: BMW Verdict BMW A classy mid-sized luxury car that has effortless power and amazing efficiency, generous levels of space and comfort and a balanced mix of tradition and technology. Audi The individual results might seem as though it’s been a whitewash against the Audi, but they have been by the narrowest of margins. Surprisingly, the Audi is one with the more mongrel to its character and that may make it appeal more those that want to experience the oomph more often. But, really, we’re splitting hairs, as both seamlessly blend performance, luxury and efficiency in a similar fashion. Winner: BMW As Editor in Chief of the Drive Network, Amac is one of Australia's most experienced automotive journalists with more than 25 years experience in newspapers, magazines, broadcasting and digital more about Andrew Maclean