Harcus Parker said it has obtained documents which show the 1.2-litre petrol Qashqais breach emissions limits by up to 15 times when driven on the road.
The Qashqai is the UK’s biggest selling family petrol car.
Compensation which lawyers believe affected motorists are entitled to
Lawyers also allege they have seen independent test data indicating that as many as 1.3 million diesel vehicles manufactured by Nissan and Renault may also be fitted with devices designed to cheat emission tests.
The scandal around defeat devices has previously been focused on diesel models.
Damon Parker, senior partner at Harcus Parker, which is launching legal action, said: “For the first time, we have seen evidence that car manufacturers may be cheating emissions tests of petrol, as well as diesel vehicles.
“We have written to Renault and Nissan to seek an explanation for these extraordinary results, but the data suggests to me that these vehicles, much like some VWs and Mercedes cars, know when they are being tested and are on their best behaviour then and only then.
“These are vehicles which could and should meet European air quality limits in normal use, but rather than spend a little more on research and development, Renault and Nissan appear to have gone down the same path as VW and Mercedes and decided to cheat the tests.
Harcus Parker claimed owners of affected cars are entitled to compensation worth around £5,000 each.
Japanese manufacturer Nissan builds the Qashqai at its Sunderland factory.
A company spokesman said: “Nissan strongly refutes these claims. Nissan has not and does not employ defeat devices in any of the cars that we make, and all Nissan vehicles fully comply with applicable emissions legislation.
“The initial report from 2017, which looked at the variation between lab and real world conditions, showed variances for most brands involved. It also stated that the Nissan tested complied with all required regulatory limits.
“Emissions standards have evolved since 2017, and we have introduced a new range of powertrains to meet them.”
Renault said in a statement: “All Groupe Renault vehicles are, and always have been, type-approved in accordance with the laws and regulations for all the countries in which they are sold and are not fitted with ‘defeat devices’.”
The so-called “dieselgate” emissions scandal first surfaced against Volkswagen in September 2015.
The manufacturer admitted that 11 million of its diesel vehicles worldwide were affected, including almost 1.2 million in the UK, prompting a flurry of litigation.
In April, the High Court ruled that software installed by Volkswagen was a “defeat device”.
It emerged earlier this month that more than 10,000 Mercedes customers have signed up to a possible legal challenge relating to alleged use of similar technology.