LONDON — Despite the cloud cast by the Volkswagen scandal, automakers are proposing that they be allowed a 70 percent increase in the nitrogen oxides their cars emit, unreleased documents show, as part of new European pollution tests.

Under the new plan, cars in Europe would for the first time be tested on the road, using portable monitoring equipment, in addition to laboratory testing.

The automakers, which include Volkswagen, General Motors, Daimler, BMW, Toyota, Renault, PSA Peugeot Citroën, Ford and Hyundai, are essentially conceding what outside groups have said for some time — that the industry cannot meet pollution regulations when cars are taken out of testing laboratories. The move is occurring as Volkswagen, the world’s largest automaker, grapples with fallout from the discovery that 11 million of its vehicles were equipped with software meant to cheat emissions tests.

Tests of car emissions required in the United States and Europe take place in laboratories, where vehicles are run through drills on a dynamometer, which is the automotive equivalent of a treadmill. Automakers have found ways to cheat the tests since emissions were first regulated in the early 1970s.