If your trips are short and you don't drive long enough to get the engine REALLY warm, and you don't run it hard, I'd run the 0W20 that has the other BMW approvals that your owner's manual states....because at less-than-really warmed-up temps, that oil is always going to be relatively thick. OTOH, if you get it good and hot, and at least periodically let-er-rip, a 0W40 with no Viscosity Index Improvers would be even better than a 5W40 that has VII's. You'll have to do the research, because I have no idea which ones have VII and which ones don't need them because of using base oil that provides such a VI spread. Also, BMW LL01, BMW LL04, and/or Porsche A40 approvals would provide some extra comfort. Without those, I'd change the oil every 5000 miles instead of the 10,000 that your owner's manual probably states. However, I don't know this engine nor its oil specs, nor do I claim to be an expert, but this logic is basically how I operate my vehicles.