I'm in the market to upgrade from our 2016 GL450 to a 2019 GLS. Settled on the 2019 as we don't care for the newer body style. I've been looking for a GLS450, but not finding one with the options that are important. I have found a couple GLS550 that check the boxes for options and colors. The GL450 has been a great vehicle. Highway fuel consumption is surprisingly good for something so large. We routinely get 24mpg on the highway. I'm wondering if someone that has a GLS550 can offer an estimate of what they get at normal Interstate speeds.

 

We got 19 mpg on our trip up to Salt Lake City from Phoenix a few weeks ago, and that was fully loaded with luggage and three people averaging around 70 mph, 3 hours of the leg I had cruise set at 85 mph.

 

Thanks for the reply. That is similar speed to what we travel on the highway with our GL450, so a good comparison.

 

There you go. Detailed on the Holy Liqui Moly thread.

 

Thanks. It took me a while to see it as I was stuck at the temperature. Living in a place that rarely exceeds 78* in the Summer, it always shocks me when I see three digit temps.

 

Sure it shocked a lot of people. It was during the Heat dome in the PNW, 115 in Seattle. Not cool at all. But car carried on no sweat!

chirboiz

 

Just did a 350 mile trip in our 2017 GLS550, and got 24.8 mpg. It actually gets better gas mileage than the 2015 GL450 it replaced. Very happy with it.

 

Thanks for the reply. That is impressive and good to hear.

 

Was that 58 miles of downhill? haha.. how the heck are you getting 28 mpg?

 

nope, mostly uphill or flat. Downhill would be much greater. Secret is: positive attitude plus Liqui Moly! Exon Supreme + 93 Octane gas, but that's about it. Plus 100*Fn weather.
chirboiz,

Bob

 

Was it before or after your OE Tune?

 

Before tune, during the heatdome in PNW. I'm having too much fun right now, so i don't check MPGs, but i think if driven for mileage numbers should return same or better. Q7 after tune had much better MPGs (read 30'MPGs on a 200 miler trip). Plus, all the extra horsies/fun on tap. Time will tell

Chirboiz,

Bob

 

haha, there's no way you normally get 28 mpg. I see your average speed was 37 mph, which may partially explain it. 28 mpg would be a world record by far for a Mercedes TT V8. I feel lucky when I get 24 mpg with my ZL1 (supercharged 6.2) on long trips.

 

Just completed an 11 day cross country drive. Including primary and secondary roads

 

Mid Mo to Philadelphia in GLS550 couple years back. Ordered exactly as wanted and 4y later still lovin it with no issues at 44k miles.

 

This is during our drive today from Tucson to Phoenix. Billiard board flat for 90 miles, cruise set at 81.

 

Gents, get some Liqui Moly inthere, and you could get better numbers. Just found a bunch of DI Jectron on Ebay, so bought them. Also, preference is Exxon/Mobil Supreme, found it to deliver better performance/smoother pulls/ better MPGs than the Shell V-Power Nitro +, all 91 here in CA.
Bob