Battle of the Sixes BMW M635CSi E24 vs. BMW 630i E63

Battle of the Sixes BMW M635CSi E24 vs. BMW 630i E63

Two of a kind battle of the sixes. Battling Sixes. A couple of tasty 6-Series models go head-to-head to discover whether it’s necessary to spend a fortune for luxury, GT performance. Given the choice, I imagine most enthusiasts would take an E24 M635CSi over an E63 630i but, can the newer car offer similar thrills for less cash? Bob Harper investigates.

Sometimes I can’t help but think I’m a bit of a glutton for punishment. Being a motoring journalist can, at times, be something akin to being a small child forced to visit the sweet shop every day when they haven’t got two brass farthings to rub together. All the tasty treats are laid out in front of you, but all you’re allowed to do is smell them!

As I pull up at the HQ of Fast Classics and its sister company, Millennium Heroes, I’m that small child again; my nose pressed up against the window, but only having enough cash in my wallet to buy a couple of wheel nuts. Ah well, such is life.


To make matters worse, I’m here to sample one of my all-time favourite BMWs, the delectable E24 M635CSi. A car that, up until nine months ago, I owned. However, the differences between ‘my’ one and the car currently up for sale at Fast Classics, are obvious to me. Where mine had been to the moon and back, this fresh import from Japan has a scant 30,000km showing on its odometer. Where mine was a later, Highline example, this is the more delicately styled, chrome-bumper model, and where mine had the full swathed-in-leather interior, this one has the wonderful, houndstooth check cloth that grips you even better than the slippery leather.

With E24 M635CSi prices on the up, I feel like the man who moved his chips from red to black at the last moment, only to see the roulette ball bounce, tantalisingly, into black before finally settling in red. Once again, such is life. But perhaps there’s a cheaper option; a way you can have most of the fun of an M6, but without the potentially hefty restoration costs and without the worry that if you drive it and add to its mileage, you will be taking too much away from its value? Enter the E63 630i, which I’ve just driven to the shoot.

No, it’s not a classic, but can it offer similar thrills to the E24, for a fraction of the cost? You’ll need £20,000 these days to enter the E24 M6 fray, and I’m afraid that’ll only buy you a machine that needs a significant amount of work, and money, lavished upon it. Decent cars – those not requiring immediate expenditure – cost nearer £30,000 nowadays and, with the £100,000 M6 we saw at Classic Car Auctions’ sale last year, top-spec, low-mileage minters like the Fast Classics example are tipping the scales at £65,000. In complete contrast, an E63 630i can be bagged for around £6,000 and, if you can afford £8,000 or so, you’ll be looking at full-history machine with about 60,000 miles on the clock. So, at its most basic level, that’s certainly a lot of car for your money when compared to E24 M6 price levels.


So, are they actually all that alike, or are we comparing sherbet lemons with fruit salad chews? Well, in the engine department they’re not a million miles apart, with the E24 packing a 24-valve, straight-six that produces 286hp and 251lb ft of torque from its 3,453cc capacity. The 630i counters with an engine of similar layout, albeit with half a litre less capacity (and sorely lacking in M Power goodness and visually not a patch on the M88’s crackle black cam covers). It’s a smidgen down on power and torque – 258hp and 221lb ft in the guise we have here – although the later, N53-engined model upped those figures to 272hp and 236lb ft of torque. Perhaps, surprisingly, there’s not a huge difference in their performance levels, with BMW quoting a 0-62mph time for the M6 of 6.4 seconds, which is just 0.1 seconds quicker than the N52-engined 630i, and actually 0.2 seconds slower than the later, 272hp 630i. Over the longer, standing kilometre sprint, the 630i wins, clocking a time of 25.8 seconds compared to the M635’s 26.4.

Not a huge amount in it then and, depending on your point of view, it’s either a pretty amazing feat that an M car designed 20 years earlier has similar performance, or it shows just how far technology has progressed, given that the bottom-of-the-range 6 Series in 2004 has the same performance as the previous generation’s M car.


On the road, though, the way the two powerplants react and perform couldn’t be more different, with the older M88 being the significantly more melodic and tuneful machine. It sounds busy and menacing even at idle, and it goes through the full orchestra as the needle flies round the rev counter before it reaches its thundering crescendo and you have to engage the next gear. It’s a wonderful engine.

The 630i’s motor can’t hope to compete with the magical M but, in isolation, it’s still a pretty decent unit. It, too, is melodic, but perhaps you’ve only got the string section playing, and you miss out on the woodwind and the brass! Nevertheless, it’s still a pretty stirring engine to sit behind and, given that current BMWs that carry the ‘30i’ badge have to make do with a turbocharged four-cylinder that simply can’t cut it on the aural front, the 630i is impressive.

Back in the day, M635CSi buyers only got one transmission option – the five-speed manual Getrag unit – and, while it’s not the slickest gearbox ever designed, it’s a tough old unit with a decent, mechanical heft to it. Fast-forward 20 or so years and you could have specc’d your 630i with a choice of three transmissions – six-speed manual, six-speed auto and (very rarely) the six-speed SSG, which was an automated manual.

The driver’s spec is the manual and, thus equipped, the 630i can be quite a sporting proposition. It’s a neat and precise ‘box, albeit with a little bit of a long throw. However, the majority of 630is were bought with the auto, and it’s not a bad unit at all. In comparison to today’s super-slick eight-speeders, it’s a little bit dim-witted on occasion but, slot it into manual mode and it acquits itself pretty well.


I don’t want to dwell too much on the styling side of things because, as always, beauty is very much in the eye of the beholder. However, as far as I’m concerned, the Paul Bracq-penned lines of the E24 are yet to be bettered. It has it all, from its jutting, shark-nosed snout to its pert rear end, plus all the right curves and straightlines in the middle. For me, this model provides the iconic, BMW coupé outline. But, for those of you not stuck in the 1980s, I can see why you might hanker after the E63 6 Series. It was a shock when it arrived in the mid-noughties, but it’s aged really well and has some great design elements. Consequently, I reckon that in a few years’ time, it may well be viewed as a modern classic. But, for the time being, the E24 certainly gets my vote.

Overall the E63 is a slightly larger machine than the E24, being 65mm longer, a significant 115mm wider and 20mm taller. Where you really notice the extra width is when sitting inside the 630i, with a much larger centre console separating the driver and passenger. But, in either car, those occupying the front seats don’t want for space – there’s plenty on offer.

Those in the rear aren’t quite so lucky, although it’s the earlier car that’s slightly more commodious – but not by much. For the overall size of it, the E63 is particularly mean with its rear seat legroom – I can’t sit behind the driver’s seat in one, but I can just manage it in the E24. It’s uncomfortable, but possible.

Of course, the E63 is packed full of gadgetry that an E24 owner could only have dreamed of. Goodies such as a CD player, sat nav, climate control, Bluetooth phone connectivity are all on offer – the way technology moved on between the 1980s and the 2000s was simply astonishing. You could, of course, argue that all this equipment in the E63 simply adds weight and doesn’t really add to the driving experience but, despite all the electrical gubbins in the E63, the 630i was commendably light – at 1,475kg, it just snuck under the M635CSi’s 1,500kg. What’s more, when you’re not in the mood for that back road blast, the 630i’s superior technology and soundproofing does make it a calmer place to while away the hours.


However, if you do venture off the main roads, there’s no doubt in my mind which is the more entertaining companion – the E24 by a mile. It’s not because it’s significantly quicker than the 630i – it’s not – but it’s just so much more involving to drive. For starters, there’s more feel through the steering; it chats to you as the front wheels travel over road imperfections, and you’re never in any doubt about what’s going on at the front end. The rear’s more playful – partially down to its lower grip levels – but also because you can feel what’s about to happen at any given moment through the driver’s seat. You feel like you’re at one with the car; you become in-tune with its every nuance, and have plenty of time to make necessary inputs or corrections. And all the time there’s that sonorous, straight-six singing away to you, encouraging you to try harder, to delve a little bit deeper into its armoury.

The 630i is entertaining in its own right, but it’s as if BMW installed another layer of interference between the chassis and the driving controls. Consequently, driving it swiftly just isn’t as rewarding as in the E24. It feels slightly remote, although there’s no doubting it does what you ask. The steering is responsive and it’ll change direction faster than you might have expected, but the transparency of the original Six has been lost in translation. The E63 is a good car, but perhaps not a great one when it comes to tackling the back roads.


I’ve already mentioned the fact that an E24 is going to cost you significantly more to buy than an E63 and, when it comes to maintenance, the E24 could be the costlier of the duo, too. The simple fact of the matter is that the M635CSi is now an old car and, even if you buy a mint example, there’s going to be some remedial work necessary – parts deteriorate from a lack of use and, however good your M6 is, there will always be the dreaded spectre of rust lurking somewhere. Karmann didn’t really do much in the way of rust prevention when it built these cars so, nowadays, its bodywork can represent something of a ticking time bomb, especially in the UK’s predominantly damp climate.

You should have no such concerns with an E63, though. This model simply doesn’t rust; well, not yet, at any rate. What’s more, scheduled servicing isn’t going to break the bank. What you do have to watch out for, though, are problems with all that technology – DVD drives for the navigation and Bluetooth modules are expensive to put right. Then there are the coil packs if you have an N53-engined example. So, if you’re planning to do a significant number of miles in your 6 Series, there’s no doubt that a 630i will be a less wallet-wilting experience.

In the final analysis, I’d have to say that the E24 is the car for me. Sadly, though, my dad doesn’t own the sweet shop and I have to save up my own pocket money to visit. So, unless that lottery win comes along, or freelance journalists suddenly become mega-earners, I’m going to be stuck with the penny chews rather than the finest chocolate money can buy. Nevertheless, I’m happy with that, and a 630i would fill the void left by an M635CSi – it’s quick, moderately entertaining and a good cruiser. Not so much a replacement for the E24, but a very acceptable substitute.

THANKS TO Fast Classics Tel: 01483 338 903 Web:

As different as chalk and cheese.

Above and right: Both models feature clear, easy-to-read dials. Right: There’s no doubting the difference that 20 years makes, in terms of interior tech. On the flipside, there’s a good deal more to go wrong in the E63.

There’s no doubt that owning an E63 630i will be a less wallet-wilting experience than the E24 M635CSi.

The ‘modern’ N52 engine that powers the 630i lacks the drama of the M635CSi’s sonorous BMW M88, but it’s a decent performer, nonetheless.

The E63’s Bangle-inspired styling was controversial from day one, especially at the rear.

The M635CSi’s 3,453cc straight-six produces 286hp, and can push the car to 62mpg in 6.4 seconds.

The E24 6 Series was neatly styled from every angle.

Left: Simple, period styling in the M635CSi E24. A five-speed manual was the only transmission available on this model.

There’s no escaping the fact that the M635CSi is an old car now and, even if you buy a mint example, there’s going to be some remedial work necessary.

However good your M6 is, there will always be the dreaded spectre of rust lurking somewhere

Wonderful houndstooth check cloth that grips you even better than the slippery leather

BMW E24 M635CSi  E63 630i
Engine: M88 straight-six N52 straight-six
Capacity: 3,453cc 2,996cc
Max power: 286hp 258hp
Max torque: 251lb ft 221lb ft
0-62mph: 6.4 seconds 6.5 seconds
Top Speed: 158mph 155mph (limited)
Economy: 22.4mpg 29.4mpg
Weight: 1,500kg 1,475kg

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