MINI is dominating Cross Country rallying this year. Following on from its overall win (its third in a row and with seven cars in the top ten) at the gruelling Dakar Rally in January, it leads the FIA World Cup for Cross-Country Rallies, and until Peugeot’s new 2008 DKR racer arrives on the scene, it looks like there’ll be no stopping the team.
The ALL4 racer wears Countryman badging, but it shares only its windscreen, lights and door handles with MINI’s road-legal car. It’s a bespoke construction with mainly carbon fibre body panels and a steel roll cage. Nestled low down in front of the occupants, mounted longitudinally, is a 3.0-litre straight-six diesel engine that shares its block with many of BMW’s current production models.
BMW Motoren GmbH in Steyr, Austria is responsible for the development and mapping of the engine before handing it over to Alpina for production – though of course each unit is hand-built. Details of the combustion chamber appear to be a secret according to Miguel Moreira, Chief Mechanic. He does, however, talk us through the rest of the design. A carbon fibre cover is just about visible when the front clamshell is removed from the car, but little else. The injectors and common rail system appear similar to the BMW production items, though the fuel flow rate is higher.
Peak power is a modest 303bhp, though it’s produced at just 3,250rpm and there’s little gain from revving the engine further (other than it sounds great and not at all like any other diesel we’ve experienced). As ever, it’s the torque figure that matters and the MINI has around 516lb ft at its disposal, created at around 2,100rpm. This defines the character of the car and there’s just no reason to rev the engine further. Indeed, from little over idle, there’s meaningful acceleration and it pulls the big 1,900kg car out of soft and deep sand with disdain. Key to this is the turbocharger set-up. Like the BMW 535d, the MINI uses a twin sequential turbocharger layout, where the smaller turbo is always spinning. The large turbocharger is gradually brought into the loop by a valve that can be gradually or partially opened according to requirements. The operation of this valve and the control of boost pressure are mapped in detail to ensure there’s never any such thing as lag between gear changes. Indeed, sitting at idle we noted a boost pressure of about 1.5 bar, which rises to around 4 bar at the top end.
That low-down torque is highly desirable for Cross Country rallying, so a petrol engine was ruled out very quickly. To get the same performance, a larger, heavier unit would have been required, which of course would have a negative effect on fuel economy as well as packaging and weight distribution. We use the word ‘economy’ in the loosest sense here, as MINI confirmed that the ALL4 Racing uses about 60 litres of diesel every 100 kilometres when in the sand dunes (that’s less than 5mpg). Thankfully it has an enormous 375-litre fuel tank. And given the pummelling the cars get, it’s no surprise to find that MINI uses a dry sump lubrication system too. Clearly that helps reduce the overall engine height so it can be mounted as low down as possible.
Under the bonnet, there’s a refreshingly minimal number of wires and sensors. This is in a bid to keep weight down (wiring is heavy) and enhance durability. The wiring loom and ECU are bespoke built items and all the sensors are chosen to cope with harsher conditions in terms of the temperatures and movement than any road car will ever have to. We drove in mixed desert conditions for 30 minutes and came away sore and breathless; how the drivers survive long days for two weeks at a time in Dakar is beyond us, and it seems like the durability of the driver is just as important as the car.