The X1 shows that not even BMW can conquer the dynamic issues that result from a raised centre of gravity and the addition of all-wheel drive. It is quick, and has a smooth engine, but it also feels nose heavy and short on driver involvement. It is the quietest of the three at speed, too.
Audi hasn't helped the A5 Sportback's cause by hobbling it with a 168bhp engine, although it is 100kg lighter than its rivals here, and has a six-speed manual box that makes the most of its power.
It's also surprisingly appealing to drive. Its handling balance inclines towards neutral more than the BMW's and there's greater reaction to changes in throttle opening. However, it is compromised by steering with too much friction and not enough feel.
The A5 wins the contest of the cabins unopposed. There's nothing clever inside - it's all Audi - but it works. It's instruments are clearer than those in the Mercedes and the ambience is a league ahead of the BMW. It also feels naturally luxurious.
There are two reservations, though. Like all A4-based cars, the Sportback comes with a strange driving position with displaced pedals. It can also only carry four people.
These issues are potential deal-breakers; a shame as there's plenty of head room in the back and enough knee room to rival the Merc and BMW.
The Merc and BMW have driving positions beyond reproach, with preferences decided by individual priorities. That said, don't think the BMW automatically affords a clear view over every hedgerow - it's simply not that tall. The Merc also carries much more luggage.
Third place belongs to the Audi, a car undone not so much by its lack of power as its shortage of seats. A marketing decision has limited the appeal of an otherwise impressive and likeable car.
The BMW X1 is the best of the compact soft-roaders we've driven, and its success is well deserved.
But victory goes to the Mercedes - with the proviso that if you want an auto you should wait until later in the year when the old five-speed unit is replaced by the smoother, more fuel-efficient and refined seven-speed transmission.
The old way remains the best way.
Read the full test drive feature in Autocar magazine, on sale now.
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