AFTER sweeping past a significant milestone, drivers rarely slam their vehicles into reverse. Yet General Motors (GM), which last year joined Toyota and Volkswagen in an elite group that sells over 10m vehicles a year, may be on the brink of such a manoeuvre. On February 14th the American firm and PSA Group, which makes Peugeots and Citroëns, sprang a surprise by confirming that they were in talks that could lead to the French carmaker buying GM’s European operation.