The first incarnation of the dieselpowered MINI was a worthy enough little car, and a very economical one, with its 1.4 litre Toyota D-4D engine
But it offered little pretence to real performance, or much in the way of thrills on the road. However, the arrival of the second generation new MINI brought a new diesel power unit – fruit of BMW’s technical liaison with Peugeot – and significant power and torque boosts over the old car of around 25 per cent. No wonder MINI decided to award the car the Cooper D model name, for this is now a sub-ten seconds 0- 62mph car whose engine matches the torque output of the Cooper S!
With this new image, the Cooper D does now offer genuine appeal to car enthusiasts, particularly those reared on diesel. The quality of the cabin and the superb handling make it a great successor to the original Mini, but one now available with some serious diesel power. John H was one of those who quickly fell for the concept of a quick diesel MINI, and he grabbed one of the very first Cooper Ds to come off the production line, back in May 2007. He has greatly enjoyed the car over the subsequent 22,000 miles, (in spite of his wife’s insults – regarding a man of his mature years dashing around in a trendy MINI!) and generally gets around 52-58mpg economy on a run such as he made from his Derby home up to Tunit headquarters in Chorley, Lancashire. As you may imagine, John was looking for a bit more sparkle from the engine, but also the intriguing possibility of the even better economy that often comes from a more efficient tuned engine. A quick run on the Tunit rolling road dynamometer revealed that his well run-in power unit was in fine fettle, recording a healthy 115bhp at 3,475rpm and a very solid 197lb ft of torque at 2,100–2,500rpm, both figures being above factory specification. It took very few minutes to then fit the Tunit conversion and the engine was soon revving even more enthusiastically upwards in a series of test runs to see what the Tunit conversion could produce. With a few minor tweaks from the Tunit technicians, the engine peaked out at just under 147bhp, at 3,640rpm – giving a most impressive increase of 32bhp! Torque showed a similarly healthy increase to 234lb ft at 2,100rpm, holding over 230lb ft until 3,200rpm. John was particularly thrilled with this latter figure, shaming the relatively puny 192lb ft output of the MINI’s top blown petrol engine, the John Cooper Works S.
“With a few minor tweaks from the Tunit technicians, the engine peaked out at just under 147bhp, at 3,640rpm.”
We took a short run out with John and, even with three of us crammed in the Tunit MINI, he could feel the difference. He then dropped his two passengers off for a few minutes and went for a spin on his own. Returning with a big grin on his face, he reported that the engine’s throttle response, smoothness, and broad spread of torque were most impressive and was more than thrilled with the results of the exercise. I’m sure that he enjoyed that run back to Derby – I also wouldn’t mind betting that he chose “the road less travelled” to find some real driving roads on which to really stretch the Tunit Cooper D. So now John has a machine that, based of the power increase, is probably an eight seconds plus 0-62mph car, whilst retaining (confirmed by John) real life 50mpg plus economy that’s probably 50 per cent or more better than you would have any hope of getting from a standard Cooper S. And it would take a hard-driven one of those to stay with this Tunit Cooper D.
It’s another example of superb Tunit technology delivering a performance conversion that’s huge fun – and in many cases owners of Tunit converted cars actually report improved economy. Talk about having your cake and eating it! Chorley cake, maybe? I’m quite expecting John to confirm improved economy when he’s run it over a more extended period and I’ll let you know what figures he reports in due course.