In the first week after taking delivery of my 540i my avg fuel consumption was around 19.5lt/100kms. I attributed this to my euphoric driving at that time, having a new car and all

In the second week I drove more conservatively and managed to bring it down to 18.2lt/100kms. This was maintained into the 3rd week and I had even reset the computer counter to get a more current reading.

This week, with over 1800kms on the ODO, my avg consumption is at 16.8lt/100kms. I then started using the Sports mode and alternating between Sports and Normal. I was expecting my avg consumption to go up but now it's dropped to 15.4lt/100kms.

I'm not complaining...but what gives??

Is the consumption efficiency improving as the engine is now 'runned in'?

I thought that by using Sports mode I'd use more fuel but it seems like I'm getting better efficieny. Is this normal?

BTW, I'd like to state that every day I get into this car I fall in love over and over again

Even test drove a 323i station-wagon for the wife the other day to replace her MB A160. Nice little car and worth considering. We even tried the new MB B200 but that car sounded like a freakin truck so it's off our list.

It's official....I've been BMW-ed!!

 

I also drive a 545i and with all else equal, you should get worse gas mileage in sport mode because the rpm's are higher. Of course, that's with just about any model, not just the 545i.

However, my guess is that for you everything else is NOT equal. For example, what I've found about the 545i is that if I drive in slow traffic for a few days and get a speed avg of 35mph, my gas mileage is MUCH worse than if I can average 55mph. If I can average 75mph on a trip without traffic, I get INCREDIBLE gas mileage.

My point is that if I drive in Sport mode, but have a higher speed average than driving in regular mode, I could actually have better gas mileage in Sport mode like you're stating.

 

My 530i experience proves that DS drviging will improve gas mileage over D driving, at least when you drive a bit sporty.

 

Average speed is probably a better predictor of consumption than D or DS modes. My E39 535i (with about 70 bhp less than your 540) would do about 9.5 l/100 km on a motorway at "normal" speeds (120-160 km/h), but 16 l/100 km in traffic. Never seen anything like your numbers unless stuck in a traffic jam, though!

 

I guess your 535i was manual and no so bad traffic, because my with my 530i Steptronic I've seen 20-22l/100 km in horrific stop-and-go Bucharest winter traffic. Normally I get 14-15l/100 km in traffic, and 10-11l/100 km on normal roads. On the highway, I get if moving 130-140 km/h 9-9,5l/100 km if not accelerating hard and if I go with 180-200 km/h I easily get 15-16l/100 km.

 

No - it was an auto. I haven't a clue how bad Bucharest traffic gets, but I'm quite ready to bet London is not much better! 20-22 sounds about right in stop-and-go (traffic jam) conditions, though I never tested it.

I'm a little surprised that you are getting that result at high-ish speeds, as the 535 was returning a little better (around 14-15 at 200 kph - but only measured from the instant consumption; there's never the space to do a long run at those speeds in the UK). Possibly it's because of the astronomically tall gearing in 5th (geared for 320 kph @ 5800 rpm).

The whole trick about consumption is acceleration (unless you are going for the speed record) - or rather, the lack of it. I never push it in town - what's the point in getting to the next red light 1 or even 10 seconds earlier?

 

Very correct. I've observed that powerful cars, get lower consumtion at higher speeds than not so powerful ones. I've had a E39 535i but never got the chance to cruise at such speeds in Germany. But IIRC, 535i was a bit more powerful than 530i M54B30.

 

Just - I think. Mine was a 1998 with 235 bhp; in 2001 with the facelift BMW gave it another 10 bhp; the 530i had 231... Could easily go one way or the other with a good/bad engine from the factory.