SMG_CT

Just completed a 285 mile trip between Syracuse, NY and Wilton CT. This was my first long trip in a car that I acquired this past July.

280 miles in 4.3 hours at an average speed of 65.12 mph yielded a 31.4 MPG average.

95% of the trip was on interstate highways. Cruise control was used 90% of the time

Tire pressure was 35 lbs in all four tires

Purple TW

Now that’s quite interesting – I assume this is a petrol jobby ?

All I can say is “bad luck” – I’ve just come back from 4hrs there, 4 hrs back (two wheel drive), motorway driving, cruise control set at 65mph, at a consistent 38.5mpg.

Before I dumped the “low rolling resistance tires”, I could expect around 41 to 42mpg. It’s these “long runs” that really give you an average – but I’m surprised that 4WD uses up so much more fuel

For reference, mine is an E350 C207 CGI, natural aspirated, 2009, rear wheel drive. I’m not gloating here – I’m genuinely curious – passed a couple of S Class 400’s AWD on the way, must admit, they look tempting ……

SMG_CT

Yes, my E350 4Matic Coupe has the 3.5L CGI (gas) engine.

Based on the photo of your E350 Coupe, it appears that you are based in the UK. Given this situation, it it possible that we are using different gallon measures?

• 1 Gallon (US, Fluid) = 128 Ounces (US, Fluid)
• 1 Gallon (UK, Fluid) = 160 Ounces (UK, Fluid)

• Your observed 38.5 MPG is 22.6% better than my observed 31.4 MPG. However, you did have the advantage of a 25% larger gallon.
• In addition, a RWD car will generally get better gas mileage than an AWD car due lower weight and fewer moving parts in the drivetrain

BTW: I just switched from the original Michelin MXM4 Primacy M&S to Vredestein Quatrac 5 tires.

According to US Mercedes windows sticker, the "expected" EPA highway mileage for my car was 27 MPG. Under "real world" conditions, 31.4 MPG is a 16.29% bonus over the 27 MPG under "ideal" conditions.

I am more than pleased with this fuel efficiency experience.

Purple TW

Well spotted - this goes a long way to explaining the (apparent) discrepancy

People I talk to are surprised at what these things do to the gallon on the highway - but it's all in the tech, and that's what Mercedes do best .....