The Office of Fair Trading is to examine potentially misleading pricing practices.
Industry sectors to come under scrutiny will include car hire and insurance.
It will look into issues such as drip-pricing (where the cost of an item increases through the buying process), baiting sales (advertising discounts but only a few items are included) and reference prices (artificially increasing the price to make the discount look more attractive).
In a separate study, the watchdog will also look at how the habits and personal information of web users are used to created targeted online advertising.
Heather Clayton, a senior director at the OFT, says: “These studies will ensure that we keep up to date with the latest developments and, in particular, on how new pricing and advertising practices are emerging and evolving online.
“It is very important that the OFT’s approach to potentially misleading practices remains well-informed by a sound evidence base, so we effectively protect consumers while allowing firms to compete freely.”