Despite spats, Germany and France have come a long way

France and West Germany are trying hard to wipe out the smear of the two wars they fought against each other this century. And they are almost succeeding. At the 43d Franco-German summit this week in Rambouillet, just outside Paris, the two countries agreed to increase military and industrial cooperation and stressed their determination to speed European integration. To symbolize this European goal, customs formalities for people traveling between the two countries will be abolished in the coming weeks.

The agreements were marred, however, by a diplomatic spat over German Chancellor Helmut Kohl's exclusion from ceremonies next week marking the 40th anniversary of D-Day. Mr. Kohl reportedly had believed his presence at the ceremonies would mark the reconciliation of the Allies and Germany. But the French government decided not to invite him after Resistance and veterans groups here expressed opposition.

At the summit's concluding press conference, French President Francois Mitterrand and Mr. Kohl tried to minimize the controversy. Both denied that Mr. Kohl had ever sought an invitation to the ceremonies, even though senior European and American officials have said he requested one through intermediaries. Moreover, Mitterrand announced that he would meet Kohl in September to commemorate the war dead of both countries at Verdun, the scene of numerous extraordinarily bloody French-German battles during World War I.

The effort both leaders made to defuse the D-Day row shows how far the two countries have come since World War II. The two countries are tied formally by a 1963 friendship treaty and constitute the core of the European Community.

In contrast, France believes its former wartime ally, Britain, is the leading stumbling block to European progress. Mr. Mitterrand has not hid his disgust with British Prime Minister Margaret Thatcher's demands for a rebate from the Community.

In a major speech last week, the French President called for renegotiation of the Common Market's treaty to strengthen cooperation in areas such as education, security, business, and politics - and, in a clear reference to Britain, suggested that those not interested could stay out. A poll released this week by the European Parliament showed that some 41 percent of Frenchmen feel even stronger than their President. They want Britain to quit the Community immediately.

The French-German summit at Rambouillet was designed to put more pressure on the British. Chancellor Kohl expressed his ''total support'' for the Mitterrand proposals for strengthening the Community.

Both leaders billed the new cooperative agreements they signed as important steps toward that goal. The agreements included plans for joint construction of an antitank helicopter, the creation of a group to study the possibility of producing a military observation satellite, and other groups to look into the possibiity of projects for satellite television, cellular radio, and space programs.

The military projects are the most significant. To keep Germany from going neutral, Mitterrand has been pushing the concept of a ''European'' defense effort. Franco-German cooperation would naturally be the core of any such arrangement.

In this light, the decision to produce some 427 helicopters marks a big step forward. The two countries had failed disastrously during the 1970s to agree on joint production of a new tank, and no joint military project had been launched since the end of the 1960s.

French officials said more defense agreements will follow. As many as 50 projects are being studied by the two governments, they said. The key ones are an antitank missile and a new fighter airplane.

''This helicopter agreement is crucial,'' an official said. ''It's a sign of how important both countries view cooperation.''