Back in August it was confirmed that on 1st November the Committee of Advertising Practice (CAP) guidelines that covered fixed line broadband from the 1st April would also govern advertising and other marketing material for mobile phones and mobile broadband.
The short summary is that in any marketing any speed claims can only be made if the provider can show that 10% of the customers are able to get that speed or faster. Crucially this is not based on a paper based projection, but the providers must have measured the speeds, and if they are targeting a specific part of the UK the evidence should be relevant to that area e.g. an advert campaign attempting to sell mobile broadband as ideal for those living in rural parts of the UK would have to base its speed estimate on testing done in a similar geography.
By and large the mobile providers with the months of advance warning have toed the line, so for example on the EE website they simply claim 5x faster than 3G (source: Ofcom data) at around 8 to 12 Mbps (source: EE data). Other providers sites simply avoid any mention of speed, just stating the technology type available on their network, relying on the public knowing that a standard 3G device is probably slower than HSPA+, that is probably slower than 4G.
Testing mobile broadband speeds is very complex, and actual speeds even in ideal conditions will vary between handsets and mobile dongles, once you add the clutter that buildings introduce, how busy a devices CPU was, factor in the weather and the variability of contention due to the movement of others through the area, there is plenty of scope for an individual never seeing the claimed speeds in an area where even the testers claim much better speeds.
With fixed broadband, where consumers have not kept on top of all the rule changes (and why should they have to), we are seeing people confused and worried that if they change provider their service will be substantially slower, as after more than a decade of the maximum possible speed being advertised people are still working to that assumption.
The advertising may be more honest where speeds are mentioned, but it is going to result in the growth of the use of words like superfast, or the old phrase of 'high speed internet' which has been around since the days when 56k dial-up modems existed, that has been revamped to often just mean the latest and greatest product delivering an Internet connection.