BMW 6 Series Review (2003-2010)

What is the BMW 6 Series?

BMW started selling the 6 Series in 2003. The E63 6 Series Coupé was the first to arrive in showrooms, with the E64 6 Series Convertible following a few months later.

Fans of BMW grand tourers had been waiting a long time for the 6 Series, with the original E24 model having gone off sale in 1989. Yet not everyone felt the wait had been worth it, with the styling in particular singled out for criticism. Some disliked the iDrive rotary control system, a feature that's been a fixture in BMWs since.

Yet the combination of a broad variety of engines, ranging from fast but economical diesels to creamy V8s and even the screaming V10 M6 meant that the 6 Series found plenty of buyers – and BMW followed up with a replacement all-new BMW 6 Series in 2011, though there was no M version of that newer car.

How practical is it?

Whichever version you choose, there's plenty of space for the driver and front-seat passenger. Rear-seat space is tight, but the 6 Series coupé at least offers a decent 450-litre boot, even if the convertible has less luggage space than the coupé.

This generation of 6 Series was never tested by Euro NCAP, but the E60 5 Series on which it was based scored four out of five for adult occupant and child occupant protection when tested in 2004.

What's it like to drive?

There was nothing controversial about the way the 6 Series drove. Based on the same platform as the brilliant E60 5 Series, but with a shorter wheelbase, BMW's engineers had the perfect base vehicle from which to develop the 6 Series. It handled impeccably, with BMW's trademark rear-wheel drive balance and poise.

To start with, the BMW was available with one engine – a 4.4-litre V8 with 333bhp. Badged 645i, the car achieved a 0-62mph time of 5.6 seconds. This V8 engine sounds fantastic, with a deep bass-heavy burble that makes you want to drive everywhere with the windows wound down. In the autumn of 2005 the engine was uprated to 4.8 litres, and the car rebadged 650i.

In late 2004 a second engine option was added. Badged 630i, this 3.0-litre six-cylinder model was just 0.7 seconds slower to 62mph than the 645i V8. It may not deliver a soundtrack as compelling as the V8's, but it's certainly no poor relation.

The sensible option is the 635d. The twin-turbo six-cylinder diesel has 286bhp, but the figure that matters is the 427lb ft of torque. That's serious pulling power, and means the 635d can rival the petrol models for real-world performance but with much lower running costs. Being sensible is rarely so much fun.

There's nothing sensible about the M6, with its 500bhp V10 engine and seven-speed SMG (Sequential Manual Gearbox). With its big alloy wheels, rubber band tyres and carbonfibre roof, this is the 6 Series at its most belligerent.

While the M6 is the performance flagship of the 6 Series line up, every 6 drives well. The regular models are rewarding from the driver's seat, and surprisingly affordable as used cars when you consider how much the original owner will have paid.

Technology, equipment & infotainment

As a new car, the 6 Series was offered in standard specification, as well as SE, Sport, and Edition Sport trims. The Sport models have larger alloys and firmer suspension. For imperfect British roads, we prefer the suspension settings of the standard and SE models. All cars have cruise control and climate control, although early cars may not have Bluetooth connectivity.

The 6 Series also features a relatively early incarnation of BMW's iDrive rotary controller, which can take some time to get used to using.

BMW 6 Series running costs

If you care about running costs, don't even think about buying an M6. The Convertible achieved 18.6mpg on the combined cycle and emitted 366g/km of CO2. These figures are derived from the old NEDC test procedure, which tended to overstate a car's real-world economy. In reality, expect to see the fuel gauge sink fast unless you are very gentle on the throttle. Which, of course, you won't be.

Insurance will be costly, too, as the M6 Coupé and M6 Convertible both sit in group 50. Expect to pay £200 or more per corner when the time comes to buy replacement tyres.

At the opposite extreme sits the 635d. Being a diesel, it's much more fuel efficient than the other models. Official figures suggest fuel economy of 41mpg is achievable for the coupé, slightly less for the convertible. Mid 30s mpg is likely.

Other running costs will still be quite high, though. The 635d is in insurance group 47, so premiums will be costly.

If you want a petrol 6 Series that will go easy on your bank balance, look at the 630i. It's in insurance group 45, so will be slightly cheaper to cover than other models. However, it will cost more to fuel than the diesel. Expect 25-30mpg or thereabouts.

The 645i and 650i are thirstier, returning 20-25mpg. Despite the extra power of the V8 petrol engines, insurance costs will be similar to the 630i's.

In terms of Vehicle Exise Duty, the diesel sits in the £265 a year band (2020 rates). The 630i is in the £330 car tax bracket. All other models attract the top car tax rate of £580 per year.

BMW runs the Value Service scheme for cars three years old or older. This reduces the cost of servicing and maintenance through the franchised dealership network, but still uses genuine BMW parts.

Realistically, though, servicing will be cheaper at a good independent specialist. There are plenty of knowledgeable BMW experts outside of the franchised network.

BMW 6 Series reliablity

So far this car review has been full of praise for the 6 Series. This is where the picture becomes less rosy.

Problems with the car's electrics and engines aren't uncommon. Be particularly wary of the V8 models, which can leak oil. There are fewer problems with the 630i, another reason to consider this a more sensible buy than a V8.

Whichever engine you go for, make sure the iDrive infotainment control system is working properly. Sometimes this starts to behave erratically and it's not the kind of thing a DIY mechanic can fix. And if you are looking at the convertible, make sure you raise and lower the roof to check the mechanism still works properly. A convertible roof specialist should be able to fix any fault for less than a BMW dealer would charge.

It pays to find a car that has a full service history, given how complex the car is and how expensive it is to repair if faults develop. The trouble is the E63 and E64 6 Series are at that pre-classic car stage when used prices are low, and owners may be tempted to cut corners. You may need to look at two or three cars to find one that is still getting the TLC it deserves.

You don't have to rely on just a test drive and your own judgement, either; some specialists will look over a car for you to check for any faults. This will cost £100 or more, but it's a small cost compared with buying a used BMW 6 Series that turns into a money pit.