Now there is renewed interest in their offers, especially as incentives to buy cleaner vehicles apply to them as well as mainstream dealers.
Operating in what car manufacturers sometimes call a “grey market”, mandataires buy cars abroad and sell them on.
Germany, Italy and the Netherlands are often listed as source countries and the EU’s single market makes it all legal.
How mandataires, and the trade platforms they use, get such good deals on new cars is always a delicate subject.
Car hire companies, including bank-owned specialist companies that work only with businesses, and large companies with big sales forces are often cited. They then sell on extra vehicles, with the large initial discount for bulk orders meaning they still get a profit.
Both Renault and PSA (which makes Peugeots and Citröens) have in the past said they will stop giving big discounts for fleet sales, even if it affects the number of cars sold and their position in popular vehicle lists.
They say the discounts mean they do not make high enough margins.
A quick internet search shows sizeable discounts compared to list prices from concessionaires (main dealers): up to 46% on new cars.
As some UK readers who have brought their cars over to France know, the formalities to get a car registered here can get complicated.
Mandataires say they will handle all the paperwork for you, with customers simply having to pick up their cars from their garages as they would if they bought from a concession with a motor manufacturer’s logo on the wall.
Prices might be attractive, but mention buying from a mandataire to most French people and they will recall past scandals. A few companies took deposits and then disappeared, and there are worries about guarantees, servicing and even being sure that your new car is “really new”.
Cyril Gayet, of Tarn-based Gayet Automobiles, which has operated as a mandataire for 40 years, said: “There is really no mystery to the business.
“Once you know where to look, there are platforms where fleet buyers, and others who have ordered many cars, sell the ones they have over-ordered.
“They want to sell them and so offer the big discounts, which we pass on and they do the importation work.”
He said that once the cars have been sold, concessionaires look after the servicing and guarantees, which legally cannot be tied to the place of sale.
“A Citroën remains a Citroën, and is looked after by the Citroën network. It is the same for other makes.”
Céline Kastner, of the Automobile Club Association, said the increasing number of mandataires and their attractive offers meant that buying from them could be a good idea, as long as buyers are vigilant.
Some people have seen what seemed good deals turn to nightmares, she said.
Sellers’ reputations are of particular concern. Fly-by-night operations are not unknown, while equipment levels car vary between countries.
Other considerations include price and the time it takes for delivery.
For second-hand cars, one major problem with mandataire-imported cars remains faked kilometrage.
This is easier now than it was, as digital counters can be changed with boxes available for €150 on the internet.
“Both the buyer and the mandataire must check log books and documents to insure against this before any money is handed over,” Ms Kastner said.
“An EU study showed that between 5% and 12% of transborder secondhand car sales were affected and the accumulated effect on the economy was €6 to €12 billion. Checks are essential.”