Clement63

Mine is a 2011 W212 E250 1.8 CGI with slightly over 100,000km on the odometer. I recently serviced the car and had the spark plugs replaced (original Platinums) but am still far away from the published highway mileage..in my last run I was very light on the pedal but only got 11km/l on Ron 95 petrol. Published is 14km/l

How do I get closer to the published numbers?

kajtek1

fuel consumption number is meaningless without kept speed number

93srvman

Was the mileage bad before your spark plug change as well?

Clement63

Yes - hence the spark plug change

Clement63

Yes ofcourse - legal speed limit here is 110km/h on highways ..kept to +/- 20km/h of that and 90% of the time to 110km/h.

Am guessing the auto 5 speed gearbox is not the best for high speed cruising as I used to drive an 8 speed BMW before and constantly compare to that.

TeeEl

So let's see... 11km/L
3.7L = 1 gal.
11*3.7 = 40.7 km per gallon

So... just over 25 mpg? Is that about right? Yeah, that doesn't seem great.

110/kmh = 68ish mph

But as I understand it, published numbers are always under controlled environments. Constant speed, no incline, etc. Any sort of acceleration will decrease your mileage (literage?). How long are you on the highway? Do you use the cruise control? What if you try staying under 110? Maybe closer to 90. Can the display on the 2011 report your mileage, average speed, etc.? If so try resetting it before your next drive then post the screenshot.

Clement63

Yes - your conversion numbers are spot on (although I have been using the UK Gallon in my conversions 4.5 versus 3.7)

I can get a "live" fuel consumption readout which I typically zero out at the beginning of my highway trips ((typically about 350km long (or 217 miles))

Understand the implications of inclines and impact of cruise control but in the past on my VW Jetta and BMW 3 series could get 15-17 km/l (34 to 39 mpg) so hence my exasperation..albeit they were lighter cars!

TeeEl

Yeah, I would expect a 1.8 to get GREAT gas mileage. This isn't even... good. A number of us in E550s get better than that on the highway! I don't really know what could cause the poor mileage though. I know tire pressure (or, rather, inflation level) can contribute. Over inflating means less contact with the road means less friction and resistance. But really that shouldn't be necessary. Hopefully someone with ideas on the matter will chime in.