Bruss212

Hey everyone, I’m hoping to get some information from a few of you who have different software…

All of these tune companies advertise their hp and tq numbers, which are all pretty impressive as far as gains over stock. But I’m curious what type of fuel economy everyone is getting in their 550’s and which tunes you’re running.

My brother has a kleeman tune, and from what I understand the power gains are not quite as impressive as weistec or renntech, but he averages 31mpg on the highway and it’s incredibly fast. While a friend of ours has the renntech, and makes huge power but he said his fuel economy isn’t much better than stock.

I know this is all relative, and has a lot to do with the way the car is being driven, but I thought it would be a good idea to check in here and get some real info from some of you prior to making a purchase. I drive a ton for work, and decent fuel economy wouldn’t necessarily be a bad perk on top of all that extra power.

Thanks!

S-Prihadi

Simple calculation

Fuel burn = power

Within proper RICH fuel trim limit and timing advance and extra boost ( if turbo ) one can get more power....but more fuel burn. Extra wear and tear aside.
The highest fuel burn or power requirement is when accelerating, least power is when maintaining stable speed at speed where hydrodynamic drag is not too much, I am speaking of zero incline on the road.

Each engine has its most beautiful torque zone where it is most fuel efficient. Use that region for best fuel economy.

If your tune is proper as such when the car is driven gentle, it should not burn anymore fuel than stock car...assuming all mechanicals are healthy.
It is true, in the end it is about how violent you right foot playing with the throttle pedal is when it comes to fuel economy.

There are times bigger CC engine can burn less fuel than the smaller CC ones if one knows the torque curve and fuel burn curve vs load.

If I drive my Ford Fiesta 1.6L vs my E400, the Fiesta will burn as much fuel as my E400 at 7KM per liter average.
Why ? because the Ford is so low power, I have to rev hard to 5,000ish RPM to drive it decently quick.
E400 due to its massive low torque the turbo is designed for ( city car design ), it can do same decent speedy acceleration without going pass 3,000 RPM if I am being gentle.

However, if you own big CC ( cubic capacity , displacement ) cars, the last thing you need to worry is FUEL, because that is not why big CC car exist

KEY08

I don’t know anyone who puts a performance tune on an engine and expects better gas mileage. This covers cars of all varieties ( small displacement-large displacement ). They all use their right foot aggressively as this is the main purpose of the tune.

Bruss212

I get where both of you guys are coming from. And I also understand how an internal combustion engine works. But what I’m looking for is numbers. If I can get a tune with 550 hp and 650tq and still expect 28 mpg on the highway, it might make sense in my case to get that tune over one that makes a little more power but suffers worse mileage.

KEY08

I doubt you will get an answer here as most of the tuned bi-turbos are driven hard from what I have seen. You may indeed get the 28 on the highway, but that is asking a lot depending on your average speed. At 70 in my untuned E550 bi-turbo I was lucky to average 24-25 on the highway using premium tier one and a very clean engine and fuel delivery system. You are better asking these questions of Renntech or the other tuners. At the 550 stage and high torque you are pushing the limits of the engine and more importantly the transmission. Be careful here or you may be getting zero mpg.

Bruss212

So you don’t have any actual input on the question I asked? Oh cool…well thanks for responding twice anyway.

Boarderjosh10

I have the OE tuning tune and a 2010 e550 with a NA 5.5v8.

I used premium 91 before and after tuning.

I drove 400 miles at 20mpg from Phoenix to their shop in SoCal. The drive back was 22. Doesn't seem like much but is 10% better with tune on highway miles.

However city mpg is a bit less and I use Sport mode more often than Comfort and probably go a bit quicker than most when lights are green.

Bruss212

That’s pretty substantial.

Boarderjosh10

I would ask the tuning shop about the options for the tune they are offering. On mine I think I can adjust fuel options and I think there was an eco mode or fuel saving tune but I wasnt interested in that one.

I doubt you will notice a big drop in mpg with a tune. If you notice a big drop it's probably from driving harder due to the fun tune than from the tune burning a ton of fuel, at least with tune only mods.

If you start upgrading turbos and adding larger fuel pumps and stage 3+ then you'll obviously be burning more over stock

Blkvip

mines a 12'. i avg 22mpg. mix of highway and backroads.

in house dyno tune by local shop in mass Brentuning.