You ask about the effectiveness of LED replacement bulbs.

A question you don't have to ask as the people that sell them will tell you that
they do not comply to construction and use regulations therefore they are not as
efficient as the ones that are type approved.  

As Dave said they are a fashion item except for the correctly E marked LED units
sold by reputable "dealers" or "outlets".

My car has LED lights as do many of the newer VW, Audi and I think Ford
vehicles.  My old car had LED high level brake lights but these were not type
approved as they do not have to be.  The effectiveness of them were great -
blinding anyone within 2 meters of my back bumper and illuminating the entire
road behind me when braking. Better than WW2 searchlights...........

Stuff them into a set of E38 rear lights and with the red lens they're total
crap and there is no differentiation to 5W rear lamp and 25W stop lamp.

Road regs demand 5W bulbs for sidelights and 25W for stop light so if you fit
something that has not been rated at those figures then you can rest assured
that they are crap for use on the road.

Ok now go and argue that a 100W headlamp is better then a 55W bulb and I might
agree with the simplistic view that the brighter lamp should put more light on
the road and probably does but generally (and this has been proven) the light
scatter from the 100W unit gives a worse light distribution than the stock 55W
or 60W bulb angled correctly.  Also the legal bulbs have a UV filter built into
the "glass" envelope whereas the ilea gal one do not and if, like many current
vehicles, you happen to have acrylic based plastic lens and other fittings
within the headlamp then the UV output is enough to discolour and eventually
crack these.

Another thing to consider is that LED use UV radiation (minute) and its part of
the red light spectrum so red lenses can and will degrade any output unless
specifically designed to do the job - Oh - no such thing as white LED they are
actually blue and expensive.

Your answer please.

OK Mr Gobshite - and on which specific what point am I talking bollocks
(and I now await an intelligent response of 'ALL') - be specific rather
than the abuse and arrogance the other posts from you have 'offered'

Again you are talking BOLLOCKS

I disagree - they appear better top me which is why I want to try them
Rear of lorries/motorcycles/school & public buses have them now too.
The E number is not of concern to me - but obviously poor functionality
is of concern. E numbers mean the bulb manufacturer has gone through an
expensive type approval routine. Non-E number means its compliance
cannot be verified NOT that it does not comply with requirements!

It allows purpose designed E marked LED lamp units - which is a *very*
different matter from using LED replacement bulbs in units designed for
filament types. Replacement bulbs for those must be E marked too - and
none of the LED ones are, for a very good reason. And that reason is they
are dangerous. Just to emphasise the points again they are either bright
enough when viewed straight on but useless to the side - one type - or dim
all round - the other type.

Oh - FWIW, the custom designed LED indictor units fitted to current VW
cars are not as bright viewed from directly behind as filament types and
considerably inferior to the sides. So could present a totally unnecessary
hazard in bright sunlight - all in the name of fashion.

Well not in the UK, which has [eventually] modified construction and use
regulation to allow LED lights, but to certain criteria.

A good example of UK civil service jobsworthiness is reflective number
plates: -

These were shown on Tomorrow's World about 40 years ago.

DoT (as it then was) rejected them out of hand and drivers who fitted them
prematurely were prosecuted.

OTOH Ireland was an early adopter.

Finally the UK went over to them and only cars pre 1973 could have non
reflective plates made.

Now they are obligatory, not only that if your [cherished] plate is to be
fitted to a post 2000 car, then you have to have new ones made with the BS
mark, although I suppose if they were compliant with BS you could post fix
the mark (see another thread).

Which means that they are illegal to use on the road.

You're probably right but these ones have high intensity pointing to the
rear with side clusters for the reflectors
They *may* be very good and I think I will give it a go with front
indicators first
As for E marking - the lack of it doesn't mean they don't comply, it
merely means they haven't been type approved. This could be due to tyhe
fact that it costs  so much to achieve these markings. It's rather like
saying that someone who has passed a driving test is a better driver
than someone who hasn't - which of course is not necessarily true (just
that passing proves it!).
Worth a try for £5

These simply don't produce the same light levels as a 21 watt indicator
bulb in the normal reflector.

Euro car lighting parts must be 'E' marked to conform with those regs. And
non of these replacements are - simply because they can't produce the
correct spread of light at an intensity to replace a 21 watt filament
type. The other type of LED replacement with 5mm leds 'firing' forward do
just about produce the same intensity - but only over a very narrow angle.

For safety lights like indicators etc where a wide viewing angle is
required these things are positively dangerous - they can't be seen in
bright daylight.

Take a look and tell me what you think - these seem pretty well designed
to widen the viewing angle:
http://www.virtualvillage.co.uk/Items/002510-030?

For a start there are no direct replacement LEDs for units designed for
tungsten - the optics on these lights is optimised for a point source
filament. And for things like indictors this is a very real problem in
sunlight etc - the LED replacements simply won't be as bright, or have the
same viewing angle. And it's not just a slight difference either. There
are currently no LED replacements that meet the specifications required by
law in Europe. Completely new lamp units designed from the start for LEDs
are a different matter.

They will also confuse the failed bulb warning system.

Can anyone advise me if fitting after market LED bulbs in indicators,
side adn brake lights confuse the onboard computer?
I prefer the more responsive light they offer but don't want the car
dinging me about dead bulbs!

I've a 2001 E39

Thanks
David