How £350 Will Transform A BMW 435d Into An M4 Killer

My mate Kieran Gallagher is a racing driver. He’s competed in BTCC and the VW Cup series (here’s his harrowing account of 100mph brake failure), and he’s got a taste for fast cars.

Recently, he bought himself a £45k BMW 435d xDrive. As standard, the car is the perfect all-rounder; it’ll do 155mph, will hit 62mph from standing in a scarcely-believable 4.7 seconds and returns over 52mpg. The diesel engine is a 3.0-litre turbocharged straight-six with 314hp at 4400rpm and a mighty 467lb ft of torque between 1500 and 2500rpm (both figures dyno tested).

The 435d xDrive is by all accounts astonishingly fast. But an M4 rival it is not. Until, that is, you get the car dyno-tuned, in which case you’re well into M4 territory and beyond. Here’s a dyno print-out to prove it…

As you can see, the results of an ECU tune-up have completely altered the car’s power and torque figures. Let’s start with power, which has increased from 314hp to 393hp (a boost of around 25 per cent). The torque figure has also changed dramatically from 463lb ft to 584lb ft, an increase of 121lb ft and 26 per cent. According to owner Kieran, his tuned diesel 4-series will now demolish 62mph in 4.1 seconds.

These new figures put this 435d xDrive well into - and in the case of torque, well above - the M4’s, which musters 431hp and 406lb ft. The 0-62mph sprint takes 4.3 seconds in the £57k M4.

Sure, the 435d xDrive’s suspension and braking components will fall short if both were to do battle on track, but for £350 and an afternoon at the tuning shop, it’s one hell of a deal. Colour me impressed!

Update: it transpires that the price we were originally quoted is incorrect: £599 is the official Ecotune price.