Most users of mobile broadband in the UK are stuck in a slow lane when it comes to speed, with the majority lucky to see throughput exceed a meagre 1Mbit/s, comparison site Broadband Genie has found.

In a confirmed test of 3,600 3G mobile broadband connections conducted this year, the company found that 65 percent of users were stuck below the symbolic 1Mbit/s mark, with 39 percent actually below 512K, considered by many to define the point at which broadband begins. Twenty-six percent were between 1Mbit/s and 2Mbit/s, 7 percent bettered 3Mbit/s, with only a vanishing 0.5 percent beating the 3.6Mbit/s mark.

According to Broadband genie, the problem is that these results look ridiculous when set against the speed claims made for the technology. Vodafone claims speeds up to 7.2Mbit/s - none of the users tested came anywhere near this mark - with the other networks, Orange, T-Mobile, O2 and 3 claiming 3.6Mbit/s, several times the real-world throughputs being experienced by all but a small number of users.

"Once again it would seem the mad rush to secure the early adopters has exceeded the ability of the product to live up to over-hyped expectations," said Broadband Genie editor, Chris Marling. It's a real shame too, as mobile broadband can be perfect for a lot of uses, even at speeds below 1Mb."

The other unmentioned problem with these results is that mobile broadband is an expensive buy, often costing the same or even more than fixed broadband for considerably lower throughput.

The main networks currently charge between £10 and £15 per month for a mobile dongle, which will typically come with a long contract period and restrictive download limits around the 3GB level.

Interestingly, O2 also throws in free Wi-Fi access via The Cloud and BT's OpenZone, which would likely offer much better performance for users who can find one of these access points. Cynics will point out that O2 probably has to offer such access to make up for its more modest 3G network coverage - the company has faced criticism in the past from telecoms regulator Ofcom for the speed of investment in its network.

"I simply think that it is a fledgling technology that has a lot of problems to overcome. Hopefully the release of more spectrum, better dongles, improved HSDPA coverage will all help, but for now the limitations are there for all to see. Its still really useful, but consumers need to know what they're getting into," said Marling to Techworld.

Meanwhile, Motorola and Chinese company ZTE reckons that the throughput achievable with the next generation of mobile broadband should be around 20Mbit/s.