The Golf is six years old, twice the age of the somehow far less popular Opel/Vauxhall Astra. Ford of Europe's new Focus ought to be pummeling its elderly rival but that isn't happening either. Toyota, Hyundai, Peugeot, Renault, Kia – the list of major makes selling cars in the C segment which Volkswagen's long-time king stays ahead of is long. What is the Golf's secret?

There was no crowing from Volkswagen UK when the car overtook the Fiesta to become the country's best seller earlier in 2018. That wouldn't be the brand's style. Everything from the way it looks to how it's advertised is understated.

TV spots, online and printed media marketing all have the same message, which tends to be, 'pay a little more and be part of a desirable club'. The irony in this is similar to what applies to those who buy Audis, Mercedes and BMWs: the more popular those brands have become the less exclusive they are. But is that true? Not necessarily, as the Big Three's vast number of models prevents any one car becoming too ubiquitous. Seeing other C-Class estates everywhere? No problem, trade it in for a GLC. Or a GLC Coupe. Or a GLA. Or any number of choices in the Mercedes-AMG line-up.

What Volkswagen alone among all brands has also mastered is pricing certain versions of the Golf at true luxury car levels. The GTI is the best example of that. This goes back to the 1970s, each car slightly faster, slightly better equipped than the previous generation. And usually, a touch better looking to boot. Where the real money is made though, is in the R series. There's even an R estate and people really do pay in excess of GBP35,000 for these.

Britain is the world's number one market for R cars, the 200,000th such vehicle from this sub-brand having been handed over to a customer in July. Again, what other brand in the C segment could sell cars at this level without massive discounting? Buy an R estate and people's reactions will likely be "I didn't know VW did one of those, it looks great and I bet it goes" rather than "How bad is the resale value of THAT going to be?". Because, being a Golf (any Golf), it's going to be worth a bit more than the competition at trade-in.

Volkswagen's top seller across Europe is also the UK's number two model, way ahead of the Qashqai but a long way behind the Fiesta, the nation's long-time favourite. Numbers for September were not public at the time of writing but as at the end of August, the Golf was a staggering 15,000 units clear of the Focus. Moreover, sales are running at more than double that of the Mercedes A-Class, the only other C segment hatchback in the top ten.

It's been an especially good year for VW in Britain with the brand having topped the sales charts for three months in succession. In August, it was only just ahead of Ford (11,255 versus 11,208) and a Volkswagen insider told me recently that there could well be Golf supply issues. We shall see if that's a problem once the SMMT announces registrations data for last month. And don't forget that production of the new Focus is still ramping up and the old model has been on run out.

VW has been keeping quiet about this but it also has issues with the GTE, one of its two electrified Golfs. This plug-in hybrid has been by far the better seller in Britain compared to the fully electric e-Golf, likely due to the TV ad. Trouble is, supplies dried up some months back, the GTE being one of many variants awaiting certification for WLTP. The same applies to the Passat GTE.

It isn't just a case of waiting for the testing authorities to eventually get through the backlog of variants, each of which has to be freshly tested via a long and complex process. There have been claims that both cars will need to be re-engineered to take fresh battery packs so as to slip back below the key 50g/km CO2 barrier which they now exceed due to WLTP regulations. Above that level, such models no longer qualify for government incentives worth multiple thousand euro, which is what has happened in Germany. Other manufacturers have the same issue for certain of their own electrified vehicles but no doubt Volkswagen felt that it should pull any cars from sale which could be seen as having 'excessive' emissions, notwithstanding the loss of tax breaks for owners.

Will any of this greatly effect the ongoing success of the Golf? Not too much, it would seem: the GTE only makes up a small percentage of the model's overall sales. What may happen is that the e-Golf could benefit, especially as the public continues to warm to battery cars as the word gets out about better range.

So much for the BEV and petrol-electric hybrid Golfs; the real volume is in the turbocharged petrol versions, TDI sales having fallen substantially for obvious reasons. The latest Golf R had eluded me until recently so when the chance arose to try out the car which sits at the top of the Golf tree, I had to jump at it.

The estate, which is what I drove, is beautifully understated. Not even a hint of the boy racer about it. Well maybe; although the four exhaust tips don't really catch the eye unless you're a Golf spotter, in which case it's instantly clear that this is the top-spec car.

Power from the turbocharged 2.0-litre engine is 310PS and maximum torque is 380Nm. Unlike rivals such as the Civic Type R, drive goes to both axles and the transmission is a seven-speed DSG manufactured by the Volkswagen Group itself.

The most recent package of revisions saw a 12+inch TFT Active Info Display screen become standard, replacing analogue instrumentation. Other than that, very little has changed since the R and other Golfs were facelifted at the end of 2016. Aside from some engine tweaks as part of compliance with WLTP, no other updates are likely now, with this model being due for replacement during the third quarter of 2019. It will probably be the star of the Geneva show next March but that's not official.

Driving the R estate it's striking how good this car still is. Volkswagen understands exactly what so many buyers in this segment want: great design, the latest tech which is easy to use and genuinely helpful rather than overcomplicated and intrusive gimmicks, a high quality look and feel to everything. For the R though, extreme performance is needed too, and the car delivers that: this family estate hurtles to 62mph in 4.8 seconds. Even better, its suspension copes brilliantly with Britain's bumpy roads and you can't say that about every BMW, Audi or Mercedes priced at this level or in some cases, higher.

Is GBP36,125 too much to pay for a Golf? Not at all. And therein lies the brilliance of what Volkswagen does so much better than any rival in the segment, which, let's be honest, is called the Golf class for a reason. This car has been the standard for decades, even if the Focus has sometimes had the better dynamics. As with the ongoing success of the Corolla and Civic in the US, Europeans are loyal to the Golf because it's not only a sensible choice but an emotional one too – this is a hugely likeable car.