Carmaker Mercedes-Benz is to concentrate on luxury vehicles because these offer the best chances of “economic growth and job security,” chief executive Ola Källenius said on Thursday at an online conference. The German manufacturer wants to upgrade its entry-level models in future, but there will only be four body variants in the next generation instead of seven at present, Källenius said. This could spell the end of A- and B-class models, though the company head declined to directly answer which of the cheaper models would be dropped. “I will leave the rest to your imagination,” he said. A hi…