I understand what your saying, and it will get done as soon as it can be afforded.
OK, cool.
The point I am trying to make is, how is it that over the years these things have suddenly slipped forward several years and many thousand of miles. 10 years ago cars were going on to 60k and over 5 years before they changed them. And here we are surely with new and better ways to actually produce the same item with modem technologies and methods? It just feels like car dealers are making new ways to extract money from you time and time again.
Hmmmm . . . I do sort of agree with your point of view. However, what your really need to be aware of - is sort of down to the actual car manufacturers. When they bring out a new car, one of the (many) key issues is maintenance costs (which is why they invented LongLife servicing). So when the 2.0 TFSI engine was first introduced, VW 'claimed' that the timing belt could last a stupid amount - 120,000 miles - which really is suicidal - because for the 'average' driver, that could mean 10 to 12 years for the timing belt!
But by VW stating this stratmospheric interval, they could then claim their cars cost less to maintain than say a Ford or Vauxhall (who might be claiming a more reasonable 60k miles). But once the 'honeymoon period' is over for sales of cars with the 2.0 TFSI engines, VW then sneakly, but correctly revise the timing belt interval to a more reasonable and realistic period.
So that said - even with the GTI - then yes, 5 years or 60k miles may be perfectly acceptable for the timing belt - and I have absolutley no doubt that there are hundreds, maybe thousands of 2.0 TFSI engines running at 60k miles or five years old on the original timing belt. A few may even last 6 years, but at six years, you really are dicing with an extremely high probablility that the belt will fail - and if it does, the relatively 'cheap' £250-£350 for the routine timing belt replacement will very quickly be forgotten when you get a bill for maybe £1500 to £2000 for a new cylinder head, valves, pistons (basically upto a full engine rebuild).
So, the reason why 4 years or 40k miles is recommended is simply because the 4year/40k mile service is traditionally seen as the "big one" - where most of the more expensive maintenance items may need changing. So peeps can budget accordingly (or use it as a haggling point when purchasing a 2nd hand car which is near that mileage/age). I would personally not have any problem with recommending leaving the cam belt change until a max of 5 years or a max of 60k miles - but (a) you would need to ensure that the owner/driver is disciplined and organised enough to remember to actually get the job done, and (b) a '5year service' is traditionally seen as a 'cheaper' service - so by defferring it, not only have you stung them for an expensive 4year/40k mile service, but you will now be stinging them a year/10k later!
Finally, your comment about 'newer technologies'. Rubber/kevlar cam belts do have many advantages, which is why they were used. The alternative (for overhead cam engines) is to use chain driven cams. Chain cams may be fine on 'short-stroke' Japanese motorbikes, but on 'long-stroke' conventional car engines, particularly on larger(ish) displacement engines like a 2 litre (4 cylinder) - then a single chain would need to be long - verrrryyyyy long. And long timing chains make lots of 'engineering problems'. So a better way of using chain driven cams is to use two or more chains (the Audi modern V8s, like in the S4 and RS4, and the V10s - actually have four timing chains) - but this then adds cost. And then you need to ensure that the chain is adequately lubricated - and chains do need a copious quantity CLEAN oil.
So, if you really have a problem with changing timing belts, buy the new Mk6 GTI, because the new TSI engine in that now uses chain driven cams!
