Just £3000 can put a BMW 6 Series on your drive – but it might leave the odd oil stain on it. John Evans gives a warts-and-all guide to this consummate GT
17 July 2017

Have you got shale oil welling up through your lawn? You might need it if you’re considering a BMW 6 Series (E63/64 generation) of 2003 to 2011. It loves the stuff, necking it when you least expect it and blowing it out through the exhaust, past rocker cover gaskets, through breather hoses, down cylinder bores…

Best to get that little problem on the table from the start. We wouldn’t want you thinking this was just another dewy-eyed tribute to a snazzy BMW GT powered by a choice of thumping V8s (a 4.4 and later a 4.8), a sweet straight six 3.0-litre and a sensible-as-brown-shoes 3.0-litre diesel with twin turbos.

See BMW 6 Series for sale on PistonHeads 

Who can forget its predecessor, the CSi of the 1980s? A car like that plays with your mind and wants you to see echoes of it in the one that follows. There were gasps of astonishment when the E63 did eventually turn up, 14 long years later. Folk couldn’t get enough of it. There was only the 328bhp 645Ci Coupé to begin, with a choice of manual (almost non-existent), sequential (rare) or automatic (plentiful) gearboxes. A convertible body style followed later.

The 6 Series’ four-seat cabin was even better made than the contemporary E60 5 Series’. It was not as roomy (no one older than five will thank you for sticking them in the back) but fit and finish were excellent, and remain so. The boot can take a couple of large suitcases. 

The less juicy straight six 3.0-litre, producing 254bhp, arrived towards the end of 2004. A healthy 630Ci auto coupé will crack 0-62mph in 6.5sec compared with the V8’s 5.4sec, but will slurp much less fuel – one gallon every 30 miles, 10 more miles than the V8. Sweeter-handling (it’s 130kg lighter) and potentially less troublesome, it’s the one to buy.


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BMW 6 Series coupé
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The BMW 6 Series is a superbly accomplished car, unless you’re a driving enthusiast

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Towards the end of 2005, BMW replaced the 4.2 with a more powerful 4.8, producing 362bhp and capable of 0-62mph in 5.1sec. Amazingly, economy was around 2mpg better. Economy? It was becoming a hot topic to the extent that BMW took the opportunity in 2007 to slip its Efficient Dynamics package of economy and CO2-boosting measures into the model’s mid-life facelift. The major beneficiary was the 630i (the ‘C’ was dropped from the model name), now capable of 35mpg. Extra power, LED lights, and subtly tweaked front and rear ends topped the update.

The 635d was introduced at this time, too. A diesel-powered GT was pretty novel then, but BMW didn’t muck about: the 635d’s 3.0-litre straight six produced 282bhp for 0-62mph in 6.0sec, just 0.1sec shy of the now uprated 264bhp 630i. Economy was 40.9mpg.

It’s a strong engine but the good economy and low CO2 emissions that once attracted company car buyers are not uppermost in the minds of used car enthusiasts. For them, the straight six petrol is the model of choice. Just remember to dip the oil every few minutes.

An expert’s view…


“They can leak oil — lots of it: hoses cracking or getting blocked, gaskets failing, gearboxes running dry… these are the problems we see all the time. Would I buy one? ‘Buyer beware’ is all I can say. Go in with your eyes wide open and don’t buy the first you see, or the second. I’m bound to say it, since we can offer this service, but pay for a pre-purchase inspection by a professional. We charge £102. It takes a couple of hours and we go through the whole car. That flushes out the problems.”

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BMW 6 Series problems


A ‘check engine’ light could indicate that the camshaft position sensor needs changing. Vanos solenoids and actuators can fail, leading to poor running. Oil leaks from the rocker cover gaskets, the oil filter housing and the oil lines to valve timing units. V8 engines can suffer high oil consumption, which could be valve stem seals, bore wear or perished breather hoses. Idle for 30sec and then blip the throttle, watching for smoke. The 630i suffers oil separator breather pipe issues. V8s run at high pressure, and older hoses and thermostats can fail. The expansion bottle can explode.


Check the turbos’ pressure converters and vacuum pipes. The crank dampener can separate. Inlet manifolds and swirl flaps leak. Checka faulty exhaust gas recirculation thermostat isn’t letting the diesel particulate filter soot up.


Plastic sump cover can leak fluid, requiring replacement since the filter is part of it. It’s sealed for life but not unknown for 100k-milers to have just two litres of oil left (it takes six). Check the shifts for a thump changing down, snatchy and lethargic going up. It could be pressure sensor oil starvation.


Road humps destroy the front control struts (feel for a shudder through the brake pedal) and front shocks, which leak. Lower rear hub bushes wear and springs break.


A new battery must be coded to fit.


Should be rust-free. Fabric roof sensors can fail. Check the bulkhead drain holes are clear.

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Also worth knowing…

The 6 Series hood can be troublesome but don’t despair: folding roof specialist Cayman Auto Services (01306 885566) should be able to fix it.

BMW 6 Series prices


Early 645Cis with more than 100k and some with full service history.


More 645Cis, including cabrios, but also tidy 2005-2006 630Cis appearing now, plus the first 650Cis, with sub-100k cars of all types closer to £7495.


More 2006-2008 630is surfacing with around 90k miles, plus low-mileage early 645Cis and 650is.


Many more 2007-2009 635ds with around 100k miles plus usual spread of petrol cars.


Many more tidy 2008-2010 mid-mileage 635ds.

John Evans

Join the debate


17 July 2017
This sounds like a nightmare to buy used. Did BMW consider build quality at all !

17 July 2017
racinggreen wrote:

This sounds like a nightmare to buy used. Did BMW consider build quality at all !

Absolutely sounds like a shocker, lot of flash for little cash but a headache to try and run.

But everyone keeps buying German, because it's "reliable, innit?"

17 July 2017

And you didn't even get into BMW electronics, all of which can play up or fail after a decade or so. Caveat emptor.

17 July 2017

So many apparently nice cars, that recieved great reviews when new, seeem to be riddled with expensive reliability problems. This is one I would avoid like an unusually severe plague.

17 July 2017

Maybe if you buy a decent straight 6 version cheap then plan on spending £2,000 to fix any potential faults (hoses, gaskets, sump, filters, suspension dampers) before they occur you might get to own a car of your dreams. Just don't expect Mondeo running costs though! 

17 July 2017

I doubt anyone is really intending to buy a used one of these to rach up 20K or 30K miles a year. In the context of a car which will very likely have a lower than average annual mileage, fuel consumption is somewhat irrelevant, so may as well avoid the diesels. Enjoy it for what it is, add fuel when necessary, repeat. Of more concern is the apparent question mark over reliability, but even so, you're not losing much in depreciation on an older car.

Personally, I would prefer to take a chance on a well maintained 25 year old 850i or maybe 840i than its more modern descendant, this 6 series, which even after all these years, is still ugly to my eyes. Chris Bangle has a lot to answer for, and his work at BMW appeared to be career ending. Some would say rightly so, although the board did sign off on his ideas. Not a great chapter in the BMW story, though.

17 July 2017

I wouldn't buy one of these purely on its looks, which are hideous. If I were in the market for a used GT car I'd go straight for a Jaguar XK8/XK, Maserati 3200 or a DB9, even if I had to pay that bit extra. At least you'd have something that was classy, great looking and desirable. Not a car that just looks like an ugly version of a dull 2 door saloon.

17 July 2017

No mention of the M6....?, is it an even bigger money pit.....?

17 July 2017

Could have been a very short article. "Thinking of buying a 6 series? For the love of everything, don't".

17 July 2017

Have you ever seen a stricken 6 series by the side of the road? I haven't. I ran a 635d from 6 months old to 5 years old and the only thing that went wrong with it was a need to recharge the aircon just before I sold it. I averaged 38mpg (but that compares with 44mpg in my current 640d GC). I had two XK8s before the 635d and enjoyed them, notwithstanding the sometimes wayward tail (and 23mpg) but as soon as I saw how little usable luggage space there was in the successor XK I switched to the BMW.



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