My husband and I are taking delivery of a new BMW 520d SE auto in January. We've never run a diesel before and are absolutely thrilled at the prospect of much more economical motoring. We've run Renaults, Peugeots (including a gorgeous 605) and SAABs for years and have a 9-5 HOT Aero auto at the moment. It's perfectly delicious to drive as it's used almost exclusively on long motorway runs every week (21,000 miles per year) and we put Shell V power petrol in. We'll miss the sweet running and wonderful power it holds in reserve, but not the expense of servicing and taxing it. Please could you advise the most economical way of driving our new BMW. Also, we always drive our cars very gently whilst cold, gradually letting them build up themselves until we cruise at the legal speed. Is it OK to carry on driving this way or not? I also try to avoid braking if at all possible.

Asked on 31 January 2009 by

Answered by Honest John
Your BMW diesel will take much longer to reach full running temperature on cold, frosty winter mornings. Possibly as long as 10 miles. (My Focus ECOnetic does.) So it’s vital for economy to avoid hard acceleration during the warm up. Then, taking care to watch the road as well, use the instant fuel economy read-out to see the effects of different driving techniques. There’s a big difference between driving at 50 and driving at 70 - 80. Don't try to maintain speed uphill, but obviously pull over to let anyone who does want to get past. Note that sometimes the particulate filter will regenerate and fuel consumption will rise considerably during that period. I find that using BP Ultimate diesel seems to keep the DPF cleaner and reduces the need for it to regenerate.
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