Just one in 10 people can identify the cheapest in a range of energy tariffs despite most suppliers saying they have simplified their offer, a study has found.
The Which? investigation found that the number rose to nine in 10 when the tariffs were shown in the simpler style of a petrol forecourt display.
Most energy suppliers claim to have simplified their tariffs over the last year.
But the watchdog's study found most consumers are still "baffled".
It asked those surveyed to identify the cheapest deal for using 2,100kWh of electricity a year with payment by fixed monthly direct debit.
Only 8% identified the cheapest deal out of the six leading suppliers' standard electricity tariffs, 60% got the answer wrong and 32% simply did not know.
They were then shown a hypothetical choice of simplified electricity tariffs and 89% were able to choose the cheapest deal.
They could also find it four times faster than for the existing standard electricity tariffs.
According to regulator Ofgem, around three-quarters of energy customers remain on standard tariffs even though they are some of the most expensive on the market.
Which?, a consumer rights group, is calling on suppliers to give "simple, consistent" unit prices to allow consumers to compare them at a glance, in a similar way to petrol forecourt displays.