How We Made A BMW E46 330d Touring Quicker Than An E92 M3

By now, you’ll know that our BMW E46 330d Touring - aka Gareth - is marginally quicker than an E92 M3 on track. And sure, it took the entire nine-episode series to get there, but remember…this is still a sub-£10,000 diesel estate that pulls like a whipped horse and returns over 50mpg on the motorway.

My buddy Gareth (he’s the brains behind the build and confusingly shares a name with the car) and I really love the 330d; it’s been easy to work on, has been reliable (except for a failed water pump), and hasn’t ripped itself off the subframe despite over 200 laps of my mechanically-unsympathetic approach to corners. And a near-500lb ft torque figure.

With our goal achieved, here’s a write-up of what we’ve done to the car to make it faster and more awesome than it could ever have dreamed. I’ll also tell you what’s been fun about the project, as well as a few things you didn’t see in the videos. And of course, I’ll be answering your FAQs about what’s easily been our proudest build to date!

How much did the build cost?

This is easily the most frequently asked question I get about the car, so here’s your answer: including buying the 330d for £1800, the total cost of the build came to £8480.59. And that includes £300 for a buggered flywheel, plus £104 for a gear linkage we broke. So if these parts are in good shape on your car, then the real price (minus the cost of the RaceChip we experimented with) is £7630.52.

In terms of where the money’s gone, here are prices of the individual parts, as seen on the Car Throttle shop:

• Fifteen52 Wheels: £1000
• Nankang NS2R tyres: £390
• EBC Discs & Pads: 572.84
• Eibach Coilovers: £1084.60
• Eibach Anti-Roll Bars: £410.56
• Eibach Adjustable Camber Arms: £350
• Powerflex Polybushes: £294.54
• Takata Harness: £225
• Momo Prototipo Steering Wheel: £187
• Momo Nero Gear Knob: £74
• Bucket Seat: £409.98
• 4-Paddle Clutch: 357.37
• Pressure Plate: 407.47
• Release Bearing: £90
• Turbo Dynamics Hybrid Turbo Conversion: £550
• Mapping At BW Chiptune: £350
• Full Suspension Set Up At Spires: £264
• Suspension Set Up At Local Garage: £100

Additional parts we used were:

• Dual-Mass Flywheel: £297.07
• Gear Linkage (from BMW): £104
• Water Pump: £52
• RaceChip GTS: £449

The grand total comes to £9819.43 which is, as many of you have pointed out, the cost of a nice E46 M3. However, loads of people have M3s, and I do love a fast wagon, so I’ll stick with the +160mph and +50mpg 330d. And anyway, this 330d is faster than an E92 M3 now, so an E46 M3 would be a fair way off in terms of performance.

What mods made the biggest difference?

You can throw thousands at a car to make it faster in principal, but if you don’t have the right tyres, you won’t see the results. That’s why it’s important to make performance tyres a high priority on your mods’ list. We saw a 1.5-second improvement in lap times thanks to good rubber (coupled with the Eibach coilovers which are bloody excellent). We’re now at the point, however, where the 3.0d’s massive torque figure is too much for the NS2Rs, so they’ll be swapped out for the next installment of Project 330d.

With the car handling and stopping well, the next mod we looked at was power. You’ll remember we installed the RaceChip GTS for one of the later episodes, and despite some Internet rage from people in the comments about piggyback modules like this one, believe me when I say that it really works.

The 330d was faster around the lap, had way more torque than before and set a quicker lap time by 0.4 seconds; this is a big margin when you remember that an entire lap takes around 38 seconds. Sure, it’s not as effective as taking a car to a tuner with a dyno, but for those of you looking for a quick fix - the installation takes around 15 minutes - it’s an excellent and very cost-effective way to release power and a shed-load or torque, especially on a big-engined turbodiesel like this.

One of my favourite mods we did was also the only one you can all do completely free of charge and at home: stripping the interior. I particularly enjoyed this because I’m very good at breaking things. And in terms of the 330d’s dymanics, the weight reduction didn’t make a massive difference to lap times, but really transformed the handling of the Touring. It suddenly felt more nimble and was keener to change direction, and all this with only 150kg removed. There’s probably another 100kg to come out, but we’ll get to that when we head into the second series.

Finally, the episode you all waited for: big power. Thanks to a hybrid turbo conversion courtesy of Turbo Dynamics plus expert tuning in the capable hands of BW Chiptune, we were able to unleash just over 300hp and 490lb ft of torque. The guys at BW Chiptune tell me there’s still plenty more to power and torque to extract, but what with Curburough Sprint Circuit being so small, any more than the already big numbers we acheived would have been unmanageable for me as the driver.

Was anything a pain in the ass?

Planning how to build a car is a lot of fun, but when it actually comes to unbolting subframes or changing flywheels, there’s always something unexpected that makes progress frustrating. My MX-5 is no exception. I attempted to re-skin the roof recently, and while the process sounds simple, it’s actually a huge pain, requiring drilling of rivets, installing of new rivets, a lot of head scratching and enough patience to not violently stab the new roof through the heart out of frustration.

Anyway, I’m getting sidetracked…the E46 330d by contrast has been really good to work on, and when stuff did break, it did it at the best possible time. The water pump, for example snuffed it literally as I arrived at This Is Your Garage, so Adam from VolksTechniks ordered one and fitted it for me while I was swapping out the standard suspension for the Eibachs.

Rust hasn’t been too troubling either, and to my knowledge, we didn’t snap even one bolt. The engine has proven bullet-proof, the gearbox is strong, and with the new power and torque, this wagon really flies.

I think the most annoying thing we encountered on the build was the flywheel that had too much play in it. This meant that we had to cut day one of the build short, but the second day (reinstalling the engine etc) went really smoothly, so no harm done.

In summary, then, the 330d has been a great platform to modify; reliable, strong, economical and easy to work on.

What's next for the 330d?

Gareth the mighty 330d Touring will be napping for a couple of months before we launch the second series in the new year. There are a few reasons for the break. There’s some maintenance we need to do to the car - non-stop laps put a lot of strain on a car - and the weather will be really unreliable for the next few months, so we can’t rely on a dry track for a while yet.

In terms of mods going forward, we’re looking at a limited-slip differential, a roll cage, further weight reduction, chassis bracing, even more hardcore tyres, uprated fuel pumps and injectors, more power and torque, a larger intercooler, a cast iron exhaust manifold because the aluminium one has a tendency to crack…you get the gist, there’s a lot more to come!

We also plan to take the 330d to a longer and faster track, find an even more hardcore challenger (maybe an M2 Competition?) and find out how far we can push it. I’d also be interested to see how fast the 330d is in a straight line, so a drag strip or maybe even the Autobahn might be on the cards.

I’d be interested to hear your ideas too, so let me know below!