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I just took a long-ish one day raod trip to visit a family member. I was curious to see what my car's real highway mileage would be. The trip was around 440 total miles with around 380 miles on the highway. It also includes leaving the car turned on while picking up my elderly momand loading her walker into the car. Her presence also meant I couldn't go as fast as I wanted...I'm sure you guys know what I mean...LOL. It was also raining heavily for the first 180+ miles from 7AM to 10AM, then light rain afterwards. 20.2mpg is slightly lower than expected.
Last edited by carlosinseattle; Dec 9, 2024 at 12:18 PM.
That is lower than I'd thought, especially at average of 58 mph. I wonder if weight and 4 matic makes that big of a difference. My GTS used to get 23-24 crusing at 70+ mph.
Proper tire pressure
clean air filters
spark plugs
Thanks for the feedback. I'm running 49psi on all 4 tires. I'm at 47K miles so I'll do the air filter within a couple weeks. I was hoping to wait until summer before changing spark plugs. Air filters were changed at 37K miles in the summer of 2023 so they're less than 18 months and 10K miles. We'll see if the air filters make any difference.
That indeed seems kinda low. Vehicle weight doesn't play much of a role anymore at highway speed as air resistance becomes the dominant factor. The S63's rated highway mpg is 26 mpg, same as my C63 and on long highway trips like that I've seen an average as high as 24 mpg with DISTRONIC set to 75 mph and just cruising along. Varies somewhat depending on head vs. tailwind and elevation changes, and rain does lower mpg due to the higher rolling resistance as the tires have to displace the water on the road and it cools the tires so they are not necessarily at optimal temperature. Also, the winter fuel blends yield lower mpg. DISTRONIC disables Glide mode, not that I'm ever using Glide mode, but it's worth mentioning. Also, the S63 has cylinder deactivation, which my C63 doesn't have, but from what I'm reading it doesn't switch to 4-cylinder mode when DISTRONIC is active. Did you cruise along with DISTRONIC mostly and have you noticed if it ever went to 4-cylinder mode?
Last edited by superswiss; Dec 12, 2024 at 04:43 PM.
Thanks @superswiss !! It rained most all the way down there, and 50%+ on the drive back and I generally don't use cruise control in the rain. I used distronic for less than 50 miles of the entire trip. However, it never went into 4 cylinder mode as far as I remember. I've seen it go into 4 cylinder mode around town, even in the few days since my road trip. And I only had a couple occasions where it went into Gliding Mode, mainly on short downhill sections, which were immedeately followed by an uphill section. Any effect of coasting downhill was erased by an uphill section. My normal mpg from mixed use is around 14mpg, which is also kind of low. It might be due to how I drive the car. Maybe it's best if I reduce the frequency of fast starts.
I have seen as high as 26 on I90 in the summer over in Eastern WA. Going up the pass hurts it a little but I would guess it is winter gas and weather related.
I have seen as high as 26 on I90 in the summer over in Eastern WA. Going up the pass hurts it a little but I would guess it is winter gas and weather related.
Thanks! I was wondering about your gas mileage since we're in the same area. Gas mileage wasn't a factor when deciding on a car, but I want to be sure something is wrong with my car. My understandign was the winter blend of gasoline is designed to reduce emissions, but I didn't think it had a negative effect on gas mileage. What are you getting over the course of a week, or any timeframe, in your daily driving?
LAX to SJC, non-stop, first hour of heavy rains with speed reduced to about 55MPH. Cruising speed of 77 with a handful of sprints up to 90-100 for a few seconds but I didn't want to push it since cold tires was 27. Lots of 70 to 85 due to truck traffic in the valley. Solo driver (200lbs) with with a full tank just outside of Burbank. 21 E63 in comfort. I average 16 locally.
18' S63, max I ever saw was 23, 2 hour drive up to Sacramento. 40PSI all around, 2 people, normal cruising speed, no sprints or spirited driving and used cruise control for most of the drive.
LAX to SJC, non-stop, first hour of heavy rains with speed reduced to about 55MPH. Cruising speed of 77 with a handful of sprints up to 90-100 for a few seconds but I didn't want to push it since cold tires was 27. Lots of 70 to 85 due to truck traffic in the valley. Solo driver (200lbs) with with a full tank just outside of Burbank. 21 E63 in comfort. I average 16 locally.
18' S63, max I ever saw was 23, 2 hour drive up to Sacramento. 40PSI all around, 2 people, normal cruising speed, no sprints or spirited driving and used cruise control for most of the drive.
Thanks for posting! I don't feel so bad since you only got marginally better mileage than me. I would have thought an E63 would have delivered around 25mpg on a trip like that, based on the comments from others.
I forgot to consider that I weigh 310lbs, and my mom weighs around 240. By the time we account for her walker and the other items we took along it probably came out to around 600 extra pounds.
I am averaging 18.9 mpg based on 60% country / 40% freeway driving. I have gotten as high as 28 mpg while hypermiling on the freeway here in Connecticut.
18 - 20 but I tend to drive a little aggressive at times.
My "normal" average is under 15mpg with normal use around town and things. Are you saying you normally get 18-20 in daily use, or when on a road trip? I assumed I'd get around 17mpg in daily use and around 23-25 on a road trip. That last trip was to the Oregon coast area so there we no passes. I almost drove to Montana this last weekend but took my wife's Venza instead. We hit so pretty rough stuff on the way back; black ice on bridges and ice and slush on the roadway. We saw several spinouts and overturned vehicles. I just took my time. Can;t help bu wonder how things would have gone in my S63.
I'll have a chance to take the car across the passes this Spring and Summer, curious about the gas mileage.
Since I'm only getting around 15 mpg in daily driving, do you think this means my car needs spark plugs NOW???
Carlos.... Day to day driving of mostly short trips in heavy traffic with rain and Ethanol in the gas says your fuel economy is normal. You being a 300 pounder is not a factor.
Modern cars are very picky and will tattle on a misfire with a surprisingly small number of counted misfires. Yes; it keeps track of misfires in individual cylinders.
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