Mercedes' first serious attempt to attack the French urban bus market came in the early 1970s. Their O305 rear-engined single decker was then quite new, having recently been designed to conform to a specification laid down by the German Association of Public Transport Operators (VöV). Mercedes tentatively began to offer the O305 on the French market in 1971, and slowly the sales began to build up. A major coup was the sale of 40 buses to SEMITAN, Nantes in 1973-4.

However, the appearance of a major foreign competitor in the French bus market had not gone unnoticed. These were the days before European Free Trade was talked of, and bus companies soon came under pressure from their local politicians to buy the home-grown products of Saviem and Berliet rather than foreign imports.

However, the men from Mannheim were unwilling to give up their toehold in the French market without a fight. What it needed, Mercedes reasoned, was a French partner to give the buses some local content and a French name. In this way, Mercedes could continue to sell O305s on the French market in a way that was politically acceptable to the French. As a result, Mercedes linked up with a small French bodybuilder named Heuliez, who would, in future, body O305 underframes and market them for sale to French operators. The Heuliez body for the Mercedes bore a certain resemblance to the VöV standard design built in Germany, however there was a slightly deeper roofline and new front and rear ends to Heuliez' own design.

Nantes had clearly been pleased with their batch of O305s, and headed the queue for Heuliez-built buses. Most of the Heuliez-bodied buses carried the Heuliez badge in place of the three-pointed star, and this was enough to give the Mercedes respectability in the French market. Mercedes / Heuliez O305s soon began appearing with fleets across the country. Most were dual-door buses, however a few customers (including Nantes and TCRB, Boulogne) bought three-door buses with two exits between the axles.

Mercedes developed a 'pusher' articulated version of the O305, known as the O305G, in 1977. The following year Heuliez-bodied versions began appearing on the French market, stealing a march on Renault which did not have a competing product.

All told, a total of about 1200 Mercedes / Heuliez buses were built before production ceased in 1983. They were bought by a wide variety of operators across France, although they were usually bought in addition to, rather than in place of, French built products. Only Mercedes-devotee Nantes really standardised on the type, around 160 of the total production going to this one customer alone. As production finished some sixteen years ago, the Mercedes / Heuliez is now rapidly disappearing from service. Many of those already ousted from service with French fleets have found eager new owners in former-Communist states such as Bulgaria, Poland and Russia. Few towns now retain Mercedes / Heuliez buses in service in any number.

The most devoted operator of the Mercedes O305 in France was Nantes. SEMITAN, the urban operator in the city, became so attached to its O305s that they had most of them rebodied in the early 1990s. The new bodies were, fittingly, built by Heuliez, and were to the same design as was then being built by the company on Renault PR100.2 chassis. As Nantes is in département no. 44 (Loire-Atlantique), the rebodied buses are badged as type GX44. After a while, Nantes began to run out of suitable rebodying candidates from its own fleet, so O305s from other fleets were bought second-hand to continue the programme. All in all, around 170 buses were rebuilt for TAN (including most of the Mannheim-built buses delivered in 1973-4), and Heuliez also treated smaller numbers of buses for other customers. In terms of appearance the GX44 looks virtually the same as the Renault-based Heuliez GX107, however the roar of the Mercedes engine is enough to give the game away.

Sadly the rebodying programme didn't extend to Nantes' fleet of O305G artics, although at least two other firms (STRD, Dijon and STGA, Angouleme) did try major surgery on their O305Gs to fit them with GX187-style front ends. Nantes did, however, give 20 of its artics a thorough refurbishment for a few more years of service, so these should be among the last O305Gs in service in France. Both the GX44 buses and the O305Gs are now slowly being withdrawn from service in Nantes, only a handful of each type now remain.