In tricky conditions, which of these arch-rival system works the best? Tyre Reviews decided to investigate Audi Quattro and BMW X-Drive might just be the two biggest names in the world of all-wheel drive systems. But when the going gets slippy, which setup are you better off with? YouTube’s favourite rubber expert Tyre Reviews decided to find out, by testing an Audi A4 against an example of the outgoing F30 BMW 3-series at the ‘White Hell’ test centre in Ivalo, Finland. To spice things up, there’s an all-wheel drive Jaguar XE in the mix. The Nokian Hakkapeliitta is used as a control tyre, to make sure the results are all about the AWD systems rather than the boots. Where it gets a little complicated is the Quattro name – these days it’s merely a brand that’s used for several different systems. In the case of the A4 seen here, it uses the Quattro Ultra system. This forgoes the Torsen centre differential usually seen in Audi products with longitudinally-mounted engines, opting instead for an electronically-controlled clutch pack. AUDI The system operates similarly to modern transverse Quattro-branded cars – which use Haldex-type differentials – only powering the...