1971 Mercedes-Benz 600 W100 EFI SWB

Not content with its world class W100 restorations, Cardock Classics set about making the 600 easier to live with by developing its own electronic fuel injection system. Words Shane O’ Donoghue. Images Nick Maher.

The luxury of fuel injection Cardock Classics in Ireland has developed electronic fuel injection for the W100 600

W100 600 with EFI

The luxury of fuel injection

The body was brought back to the metal during the restoration and the paint colour changed from silver to the almost ethereal anthracite grey finish shown

Cardock Classics, in County Kildare, Ireland, has established itself as a high-end restoration business that focuses on high quality and authentic renovations. Mercedes cars form the majority of the company’s orders and, in among them all, it has developed keen expertise in the refurbishment of the iconic W100 600 saloon. Indeed, the day we visit Cardock Classics, there are several examples of the 600 in storage, patiently waiting their turn to be brought back to life for their well-heeled owners.

Today, however, we’re here to see the end product, the very first 600 restored by Gar Whelan – owner of Cardock Classics – and his team, a car that has belonged to the business since 2013 and has been lovingly restored, from the ground up. The restoration is gobsmacking enough, and we’ll come back to that, but this car has also recently been used to develop a bespoke electronic fuel injection (EFI) system for the W100, a system that Cardock Classics hopes to offer to other owners of the mighty 600.

Not that you can tell at a glance that there’s anything unusual about this car. It is, quite simply, perfect. The body was brought back to the metal during the restoration and the paint colour changed from silver to the almost ethereal anthracite grey finish shown. Obviously, the wheel covers – fashioned from stainless steel – are colour-matched to the paint. Their simplicity matches the three-box shape of the 600, but never has a four-door saloon looked so elegant, so proportionately perfect.

No expense spared

It’s unmistakably a Mercedes, from any angle you care to look at it from, but what may not be immediately obvious from the pictures is the sheer size of this car. Everything is super-sized in comparison to most models in the Mercedes range from the same era. Even in this regular wheelbase vehicle. Up front, the chromed radiator grille is simply massive, but it’s in proportion to the rest of the nose, balanced by the distinctive upright headlights. Gar tells us that they might be the very last remaining new right-hand drive headlights for a 600 in the world, which Cardock Classics tracked down and paid nigh on five grand for. “Everything is expensive on these cars,” he says, “they threw the kitchen sink at it and then realised it was ridiculous and changed things a few years later. The soft-close doors weren’t in production for long, for instance.”

An undisclosed sum was paid to a German W100 parts specialist for the exhaust components on this car. Gar claims it could be the only new exhaust system suitable for a right-hand drive 600 in the world and urged Cardock Classics to copy it. Gar and his team prefer to source original components wherever possible, and though there’s a brilliant computer-based Mercedes-Benz classic parts system to consult with (this 600 received a brand new, Mercedes-Benz-supplied air conditioning compressor, for example), the parts aren’t always available. Cardock Classics tells us about the curtain hooks in the back of the 600. Apparently, Mercedes-Benz wanted £5 for each hook, but the company found someone with a box of them in Iran, willing to courier them over to Ireland for considerably less – at the same time giving Cardock Classics stock for future W100-series restorations.

The interior of the 600 is as beautifully presented as the exterior, though it’s the little details that make this car truly special. Such as the air inlets at the trailing edge of the side glass on each side that feeds the air conditioning fans mounted in the boot. These quietly send air to the rear seat occupants via low-set ducting. Meanwhile, the whole rear bench reclines at the touch of a switch. That movement is done hydraulically, as are a lot of other functions in the car. Gar winces when he talks about how expensive it was to refurbish all of that using a specialist in Germany.

For its engine overhauls, Cardock Classics usually buys as much as possible straight from Mercedes. Indeed, though the purpose of this visit is to check out the EFI system, Gar is quick to point out that there’s not much wrong with the original-fit mechanical fuel injection pump. Once they are sent off to Bosch for reconditioning, they come back like new. But Gar saw an opportunity to make the 600 even better, without altering its core character, replacing the mechanical system with a more sophisticated electronic set up.

New injectors, a mass air flow meter, oxygen sensors, engine position sensor, engine coolant temperature sensor and a control unit were sourced by Cardock Classics and the installation was designed in-house. It’s mostly hidden away, too, so a glance under the bonnet won’t immediately reveal it. Indeed, as the engine position sensor is hidden within the distributor cap (Cardock also fitted a more modern ignition system), there’s precious little to see. Until you realise that the space occupied by the massive mechanical fuel injection pump in the vee of the engine is empty.

Rather incongruously, given the luxurious surroundings of the cabin, the control unit can be plugged into a laptop and the map can be tweaked. That’s the only aspect of the system that Cardock Classics required outside help with, and this 600 has spent time being fine-tuned on a rolling road. Gar says that it now makes a little more than the 250bhp figure Mercedes claimed that the 6.3-litre M100 V8 made when it was new. More power was not the reason for going with EFI, though it’s a welcome benefit.

And despite the near three-tonne mass of this car, the engine feels lusty and stronger than such a power output might suggest. Thank the low-down torque of the large capacity layout for that. Just as impressive as the smooth power delivery, however, is how this car’s engine sits at idle. It’s easy to take such things for granted in a modern car, but EFI really smoothens out the idle. Of course, the real trick is that it can adapt to different temperatures and conditions and maintain that, making the 600 more usable more of the time.

Reliability is key

And, while the 600 has a reputation for being a car that dictators and the rich and famous were chauffeured around in, these days it’s as likely to be driven by its owner. It really is a joy to do so, too. Along with the ample performance, the big 600 is remarkably composed in the corners – once you’ve acclimatised to the body roll of course. Meanwhile, the air suspension and soft seats make it utterly comfortable everywhere else. I would have happily driven it all day. The EFI system makes that possible any time an owner wants to do so.

Magnanimously, Cardock Classics doesn’t want to keep this upgrade to itself, and it has plans to offer an EFI installation pack to owners of the 600 around the world. Or you could of course book your 600 in for some TLC in Ireland and get the EFI system installed while it’s there. The beauty of the installation is that it’s completely reversible.

Thank you to Cardock Classics for the loan of the car

Tel +353 (0)45 982620 Web www.cardockclassics.com

More power was not the reason for going with EFI, though it’s a welcome benefit

Behr air con system now back to its very best. Reclining rear seats in this restored W100.

This car has been used to develop a bespoke electronic fuel injection (EFI) system for the W100.

M100’s engine position sensor within distributor cap; new electrical relays.

Large M-B star such an iconic feature of the 600. Rear hinged side window avoids buffeting.