Number Games

Well gosh this is annoying – after spending the best part of 2 hours composing a blog post about car facts and figures it seems that Microsoft has deemed my efforts unworthy, and subsequently has updated my laptop and wiped my draft (thanks to WordPress too for failing to save it!). Whilst this is merely just another black mark against the likelihood of me choosing a Windows laptop over a MacBook it doesn’t really matter too much…it just means I will have skipped the drivel and added a few extra bits of information!

Boooo to Microsoft!

So essentially I was talking about my relative lack of understanding about the differences in engine power and torque, especially in regards to the states of tune of certain engines. In particular it seems to be 4 cylinder engines which seem to be offered with power differences ranging from minor to vast; Ford offers their 2.0 TDCi with anything from 130bhp and up, and BMW’s 2.0L diesel can be had in anything from 141bhp up to 215bhp! These kind of differences are achieved using different turbos, injector systems and various other things I don’t understand, but the leap between these 4 cylinder motors and their larger capacity V6/I6 counterparts is something I was able to experience properly first hand yesterday.

Most people in the UK plump for a 4 cylinder engine, but are V6’s really that much better?

People that read this blog with any regularity may recall that a month or so ago I was able to go on a short but sweet test drive of a Mercedes Benz CLS250, which came with a 2.1L 4-cyl diesel producing an impressive 201bhp. The 250 is the base engine in the CLS and has been criticised somewhat for being less refined and not as effortless as the other engines choices – ie not an engine that befits a grand tourer like the CLS. Coming from a car with a 6 cylinder diesel (albeit a 9 year old one) this 250 actually sounded pretty fine to me, obviously not exotic but nonetheless reasonably refined at idle and near silent even when travelling at over 80mph. Power was also ample, and coupled with the 7G automatic meant the car was relaxed and economical (circa 42mpg real life) whilst still having strong overtaking ability and acceleration.

I drove one like this yesterday…not bad!

As chance would have it, yesterday saw me sitting in the driver’s seat of a CLS350, with the 3.0L V6 diesel under the bonnet – with 261bhp and a whole lot more torque, the 350 is supposedly an entirely different kettle of fish from it’s little brother so I was eager to test it out to see if the premium for more powerful engines is really worth it. As somebody who doesn’t have a CLS as a daily driver I guess it’s a little difficult for me to properly assert the differences, but for me the silent purr of the V6 on startup is barely more quiet than the 4-cylinder’s rasp…driving around town is of course effortless speed-wise (although the low down driving position and blind spots take a little getting used to), but for me I found there to be little difference in power even when compared to my own BMW X5, a car which weighs significantly more.

Mirrors are needed in any CLS…visibility is pretty poor

It’s on the open road though that the 350 really makes itself known, as the large power reserve and seemingly endless torque really give the CLS a driving experience that properly matches the car’s outstanding looks. That’s not to say that the 250 is at all unrefined or slow, but the 350 is second only to the Porsche Cayenne S I once drove in terms of power and equals that car’s unnatural ability to make extra legal driving speeds feel like a leisurely cruise…if you want to keep your driver’s license you ought to use the speed limiter function as I found it all too easy to creep up to 85mph+ without realising it! The 350 is also available with some options which can’t be had on the 250 – things such as Airmatic suspension enhances the driving mode selectors, and the standard ‘full’ COMAND system in the 350 helps make up for some of the price increase that buyers wanting the larger engine will have to face. Fuel economy is also slightly different, with the 350 losing the start-stop function of the 250 and also a few mpg…officially the 250 gets 54mpg and the 350 47mpg, but lower both by around 10mpg to get a realistic idea of what to expect from a mix of suburban driving and motorway cruising.

The 2015 CLS comes with a few visual upgrades inside and out, but the engine range changes quite dramatically!

It’s worth mentioning that if you want a brand new CLS the choice between 4 and 6 cylinder variants has gotten a little more stark…the 250 has been replaced with a lower powered (but slightly more economical) 220 variant, now with 168bhp as opposed to 201bhp but at a lower price. The 350 engine has been left mainly untouched, but now has a 9 speed transmission compared to the old 7 that features in the 220…something that will undoubtedly change soon but is pretty important considering that fuel consumption has jumped by 10% with the new gearbox. However for those looking at used CLS it will likely depend on what is available and what you will be using the car for – this is not a backroad carver and the extra power of the 350 is only ever useful when blasting down an empty motorway or attempting a dodgy overtaking manouvere. That said many 350 will have had more options boxes ticked when new, so if you’re after gadgets like memory seats, full COMAND and adaptive cruise control you are probably more likely to find them in the more powerful car…but anyone who finds those features in a 250 will likely have the best of both worlds!

The current ML has both 250 and 350 options…neither have visible exhaust pipes for some reason

This quandry over Mercedes’ engine choices is one that also may crop up for me again in the future, with the latest ML also being offered in 250 and 350 guises; now although the CLS is by no means a small car it is quite a lot lighter (around 300kg) and so what may be fine and dandy for one car may not be quite as adequate in the other. I’ve read a few reviews on the ML250 and the general consensus seems to be pretty much that – the 250 is merely adequate and buyers spending £50k+ on an SUV would be better served by spending a little more for the 350 engine. That said the old shape ML280, which had a detuned version of the 3.0L V6 diesel in the 320 (later the 350) merely mustered 190bhp, 15 less than the ML250 which is quite significantly lighter than it’s predacessor. Moreover the quoted 0-60 time of 9 seconds is within spitting difference of my own car’s, and is still comparable to the previous genereation Range Rover Sport SDV6 – a car nobody called slow! I suspect that in real life things can get a little sluggish, but a promised 44mpg is likely the reason why most used current-shape ML’s appear to be in 250 guise.

The base engine in the new X5 is also a 4-cylinder, but effectively matches the inline 6-cylinder in the first generation car (ie what I have!)

BMW have taken a leaf out of Mercedes’ book with their latest generation X5, and have mirrored this approach by offering their own 4-cylinder diesel option (know as the s/xDrive25d depending on whether you have RWD or 4WD), the X5 has a smidge more power and given the similarities in official statistics I would assume that the new X5 performs very similarly to my own X5, which has a scant 3bhp more than the 25d’s 215bhp and beats it for torque thanks to it’s twin turbo. With a potential 54mpg (unrealistic admittedly) it would probably be my personal choice of engine as long as it has the attractive (and pricey) M Sport bodykit and wheels. Still it remains unlikely that I will be able to afford a 3rd generation car next time round and therefore my engine choices are a little more exotic than many would expect for a 24 year old!

A well specced second generation 40d may just be the best of all worlds – 38mpg and 0-60 in under 6.5 seconds!

If I decide on a second generation BMW X5 as my eventual next car then it remains almost certain that it will come with an improved version of the classic 6-cylinder diesel which BMW has produced for many years. As this is nearing the end of this post I will try not to waffle on, but with the 2011 ‘LCI’ facelift the X5 gained an updated engine range to work with the new 8-speed ZF gearbox which works so well with pretty much any car it is stuck in. The base engine remained the xDrive30d with 242bhp and those on the continent could opt for the awesome ‘M50d’ with an epic 381bhp, but well heeled UK buyers had to ‘settle’ for the xDrive40d, which pretty much matched the 30d in terms of fuel economy and emissions yet yielded 307bhp and the potential to reach 60mph in 6.4 seconds, a whole second quicker. I am not entirely convinced that the jump between these two engines will be significant, but given that the initial price difference was a mere £2k it is now apparent that there are plenty of high-specced 40d’s around for not a whole lot more than base 30d’s. Apparently real world fuel economy differs a bit too but it may turn out that the final decision to make next time around will be more focused on engines than cars per se.

One response to “Number Games

  1. I had my Land Rover tested on a rolling road recently to diagnose a problem and as a result I believe ‘power’ is simply a factor of torque x rpm so the faster the engine revs the greater the power. However this has the knock on effect that the engine won’t last very long.

    I believe some of the modern VW group engines have different engine management programs that also dictate power so in those cases a 110hp engine is actually identical to a 130hp one other than software changes – however working in the automotive service sector I know that simply increasing power by chipping leads to drastically reduced engine life.

    I prefer to have engines that have alot of torque at very low rpms so they can pull away and cruise comfortably for very few rpms so that means larger capacity diesels or big V8 petrols for me. They aren’t under as much stress due to lower rpms’s and therefore last far longer and generally have better real world mpg too.

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