For sale: a flock of Birds BMW demonstrators

Though certainly improved for the current cars, there was a time not so very long ago when the M Performance BMWs – all the powerful straight-six stuff, really – didn’t quite have the chassis quality to match their superb powertrains. Traction was iffy, the damping not really good enough, and the steering a bit mushy. There was huge potential, yet it was not totally fulfilled by the factory. 

One solution was to raid the M Performance catalogue for accessories – or for those who didn’t want to give BMW any more money, it was well worth giving Birds a call. For decades, it has offered a range of parts to bring the best out of non-M BMWs, and still does to this day. And as BMW began introducing turbocharged engines to its core models, without necessarily uprating the rest of the car to match, the Birds tweaks became more appealing than ever. Think better springs and dampers to tie down the body control, Quaife LSDs to improve traction, then perhaps a little more power just because. The overhauled cars were noticeably nicer to drive than standard, without the intensity or stiffness of M cars. Or the expense of Alpinas. 

Of course, a Birds BMW was always a pretty niche prospect. Most folk will be happy with the standard BMW offering, the M cachet is undeniable, and we all know that money spent modifying is seldom recouped when sold. So to find one of its demonstrators for sale is pretty significant. You might recognise the manual 435i, complete with its ‘B18 RDS’ numberplate, featuring on PH way back when, impressing with its more sophisticated manners and connected feel. It was a significant spend – the power, diff, springs and dampers, anti-roll bars and short shift – coming in at almost £8,000, but deemed money very well spent on an underwhelming standard car. 

Here it is once more, a dozen years later, for sale with just 11,000 miles on it. And boasting plenty more than just the aforementioned bits, with an Alcon brake upgrade and 20-inch Hartge wheels as well. With the mileage and the modifications, it really is a 4 Series like no other. And a whole lot cooler than an M4. 

The B4-35i has been listed at a dealer next door to Birds, along with three other very intriguing BMWs. The second is another F32 4 Series, a B4-35d that also benefits from suspension, engine and differential work. Unsurprisingly, given how good the prospect of a 380hp straight-six diesel with a proper LSD sounds, this 4 Series has been driven a bit more, with almost 50k under its forged alloy wheels. Again, it’s a very interesting two-door BMW, the ultimate motorway express. And it doesn’t even have tinted windows… 

The Z4 you see here is really cool, benefitting from a host of Hartge parts (including the wheels and exhaust) plus extra power, a limited-slip diff and Birds-fettled suspension. As the Z4 generation that sat between a fully fledged M car and the later M40is, a proper performance-focused take on the platform is interesting if nothing else. Moreover, it is an immaculately presented BMW convertible, driven fewer than 30,000 miles in 17 years. 

Finally, the M240i. Less modified than the rest, with just the Birds suspension work, but also with even less mileage at just 8,600. As a 70-plate car, it’s one of the last of a much-loved baby BMW, and benefits from a lovely Long Beach Blue over Oyster colour combo. It doesn’t look far off new, in fact, so it’s easy to imagine someone spending £30k on it – even with later xDrive cars almost down to that money now. 

The other Birds BMWs for sale might take a more dedicated enthusiast, given at least £25k is needed (for the 435d). The Z4 has gone up for sale at £28,950 and the B4 3.5 at £32,950. And when a 20,000-mile M4 of the same era costs similar money, that might be a tough sell. But then you’ll be doing very well indeed to find a manual M4, and it wouldn’t be a surprise to find the red car much nicer to drive on the road. Birds BMWs really are that good. There seems no better time to find out what the fuss is all about…