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Discussion Starter #1
I need to do around 2000 miles over the next 2 months in my M5. I need to do this cheaply (lol).

I'll be doing a few economy runs. What is the best economy that you have had from your M5?
 

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26mpg on the highway at around 75mph. Behind a big rig. Otherwise it drops to 25.
 

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On my way to a 450 miles trip, which had a variation in terrain for about 300 miles and straight for another 300 miles, the 25.6 mpg was what I achieved. Not to mention it was difficult to drive like a gentleman :M5launch:

If you are looking for more economy, renting a car might be the way to go.

Also, with the reliability of M5 vs a slightly newer rental car, Rental car wins.
 

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...I wonder what m5board would think about using top tier 87 octane gas on a long distance highway trip...
 

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...I wonder what m5board would think about using top tier 87 octane gas on a long distance highway trip...

I had to use 87 in the aftermath of hurricane Sandy in 2012 on the M5 and the Mini. Was kinda freaked out when they didn't have super but neither car suffered from problems under normal driving conditions.
 
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Keep itat it's sweet spot 2360 rpm 6th gear on cruise and you'll get the best milage per g.


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I've done better than 27 MpG (US) with the cruise at 85 MpH. I, however, was cheating; empty and arrow straight interstate, 40°(f)ish ambient air temp, and a slight downhill grade.
 

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I just got 25 mpg on a recent highway trip that primarily involved driving across flat, straight boring Ohio. High way speeds were between 70 and 80mph during the drive.

...I wonder what m5board would think about using top tier 87 octane gas on a long distance highway trip...
If you are driving it genitally the ignition map wouldn't try to get too aggressive so it would probably drive just fine. However you might want to check what fuel economy you achieve on the lower octane fuel. I tried running 87 in my 98 740iL with the M62 engine, and driveability was fine but average fuel economy took a dive, it went from my normal average of 20-21 down to 13-14. I am willing to bet the S62 engine with an 11:1 compression ratio wouldn't help matters over the M62's 10:1.
 

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If you are driving it genitally...
Quoted for posterity...

I managed to get ~19 MPG on the way home from TimmayFest, on average. I was also running between 90 - 100 the whole time, and have a 3.45 diff (RPM was between 3500 & 3800)

Prior to the diff swap, my personal best was just a shade over 24 MPG... also running about 90 MPH.
 

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My personal best was 23 mpg over about 400 miles a couple weeks back. Was doing 70-90 most of the time, great road with lots of twisties and elevation changes. I have only had the car a few months though, so i dont have the restraint to get better mileage yet... Dat noise!


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My personal best was 23 mpg over about 400 miles a couple weeks back. Was doing 70-90 most of the time, great road with lots of twisties and elevation changes. I have only had the car a few months though, so i dont have the restraint to get better mileage yet... Dat noise!
Four years for me and I'm lucky to get 21-22mpg. :angel:
 

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the best i got was 23.5 mpg over 1500 miles trip. I noticed that M5 do get 1 to 1.5 mpg better going 75 instead of 70. I like to keep rpm around 2500 rpm on the highway.
 

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30 mpg! (imperial gallons).....on part of the long journey home after I picked it up from the previous owner in London last summer. Was monitoring the Beast's vital signs so didn't get above 60mph on the motorway for the first quarter of the trip. Later on in the journey averaged a steady 27 mpg at 70/80mph with no passengers. Can't get it above 20 mpg now that I'm able to drive it at 9/10ths of its performance, mainly on traffic-free and interesting roads.
 

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I was so proud of my personal best of 25.2 mpg, but then i converted it to US mpg and well .. it's more like 21.2 that way, so I just cannot imagine how you can do that
 

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I need to do around 2000 miles over the next 2 months in my M5. I need to do this cheaply (lol).

I'll be doing a few economy runs. What is the best economy that you have had from your M5?
Remember that UK & US mpg are not the same when you get all the responses ;)

But for my car, in the UK, the best I have had was 34mpg driving like miss daisy was in the back, it's possible in the right situation with care.

A more realistic figure is around 30mpg on a long motorway run with minimal throttle useage, this I can get quite easily & repeatably

This is assuming the car is healthy, the MAF's & lambda sensors are working correctly, etc...
 

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When my car didn't have a tune I managed 24-25 mpg on the highway averaging 75 mph. Now with a tune I get 22-23 mpg unless I drop my speed to 60-65 then I get better 23-24 mpg.
 

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...I wonder what m5board would think about using top tier 87 octane gas on a long distance highway trip...
a) not sure anyone that needs to run 87 can actually afford the running costs of an M5

b) fuel economy is decreased by the lower octane sufficiently that it's actually more expensive to run.
 

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I've had 30mpg on a 1500 mile road trip and 27mpg on a 3000 mile road trip.
You should use higher octane stuff. The engine will lose power and efficiency using the cheaper stuff.
I put some octane 100 into it in Germany and banged it up an autobahn at 140mph and wasn't all that bad.

I saw mention of a hire car instead. When I checked this out it works out more expensive as you've still got to factor in hire costs, plus fuel on top. Obviously this may differ in other parts of the world.
 

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Discussion Starter #20
I run Tesco Momentum 99 in it all the time.

I did Aylesbury to Hull over the weekend, and then also some other driving, including some WOT, and it averaged over 25mpg (brim to brim) and after some more spirited driving on Saturday, it averaged around 25mpg again. My OBC actually under reads!

Hopefully I'll be able to get 30 if I really drive sensibly! Its only for a short time until I get another car and sell this one.
 
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