[RSBro]

Ok so the premise I'm pretty sure I know the answer to, and anytime you bump up the HP you're going to burn more fuel but I was just wondering what the average drop off has been for people after their tunes.

I'm about to have to start driving more for work and I'm looking at a Eurocharged flash, but just curious as to if we're talking 1-2mpg, 1-3, 3-5, 5+ etc on normal driving conditions. one thing I love about the turbo'd V8 is that it just sips gas on highway miles even at a high clip (75-85) so around town I'm not worried about it, but if some folks could chime in as to what they got after tuning compared to original that would be cool.

I could definitely live with 1-3mpg per tank as around town I'm barely getting 16-17 anyway, but if it's more like 3-5 that's something else to consider, assuming driving styles/conditions are similar...
thx!

[FenixMike]

Heres the thing. When youre not in boost, youre not consuming more fuel regardless of what whiz bang module you have on your car. When you add more air, you add more fuel... normal driving isnt going to impact that much unless youre an aggressive driver at which point there isnt an exact science to how much mileage you lose since everyone drives differently. That being said, tune vs piggy back will be off because a tune will set your car to proper air fuel levels to make power (or it should anyhow, im sure I tune differently than other shops) which will be richer and more boost friendly vs factory and more emissions friendly. Piggybacks cant change the target air fuel ratio (AFR in which the computer targets and adjusts to achieve) so adding boost will eventually have the computer add sufficient fuel to compensate... but again, nothing will change at part throttle unless the custom tune demands so.

As far as custom tuning goes, most vehicles I tune increase in fuel economy because I target efficiency and power as opposed to emissions which factory programs target. Theoretically by adding horsepower through boost, you are reducing effort required to maintain speeds or achieve speeds at the cost of more fuel demand for the larger air intake without more demand elsewhere, however it still all comes down to driving habits. Driving like a 16 year old kid you will likely get worse fuel, drive like me where you randomly once in a while get on it or like to roll into the throttle here and there, you will stay the same.

[mike@x-ph.com]

If you are not driving more aggressively, you will not notice a change MPG.
If you drive more aggressively, the more aggressive tune will result in lower MPG

[MEby]

My mileage went up with the BMS Stage 1 on my 2011 (N63) 550i xDrive.

If I drive modestly I get 18-19 around town on good BP 93 fuel. On the highway I get 27 at 75mph and 28 at 65mph. The car seems like it will coast forever in comfort mode. Anticipating stops in town driving is the key to getting decent mileage. Without the Tune is was 16-18 in town.

Mike

[RSBro]

Thanks, that all makes sense.
I've been getting better at slowing down in town so I'm not slamming starting/going all the time. It is just hard to keep that V8 under control ALL the time though lol.

[mikekilpatrick]

BMW stage 2 tune... Around town, about 10-14 mpg. Highway with modest acceleration and long distance driving... 22-24 mpg...

[FSociety]

Originally Posted by MEby

My mileage went up with the BMS Stage 1 on my 2011 (N63) 550i xDrive.

If I drive modestly I get 18-19 around town on good BP 93 fuel. On the highway I get 27 at 75mph and 28 at 65mph. The car seems like it will coast forever in comfort mode. Anticipating stops in town driving is the key to getting decent mileage. Without the Tune is was 16-18 in town.

Mike

Use Shell/Valero bet your MPG and Performance will improve noticeably !!!
I've used BP (cheaper price usually) but burns faster than Shell/Valero.

I agree with my piggyback tune i went from 18-19 combined to 22-24mpg combined now. Before any little aggressive driving was resulting me in horrible MPG and now the tune makes things more fun and MPG is not hurting. Got 30.5mpg on a 70-75mph Cruise Control 60 mile trip.

[FenixMike]

Originally Posted by ROBNYC

Use Shell/Valero bet your MPG and Performance will improve noticeably !!!
I've used BP (cheaper price usually) but burns faster than Shell/Valero.

I agree with my piggyback tune i went from 18-19 combined to 22-24mpg combined now. Before any little aggressive driving was resulting me in horrible MPG and now the tune makes things more fun and MPG is not hurting. Got 30.5mpg on a 70-75mph Cruise Control 60 mile trip.

Get an alcohol content gauge kit and test the fuel. Gas is gas is gas, but some sources mix more Ethanol into their fuel as it is pretty unregulated (makes it cheaper to produce) other than having a "max" amount, but some stations that may not pump much fuel can also have it separate in their tanks and dilute with more alcohol as it rises to the top. Gauges are cheap (its just a strainer with lines that separates the fuel and alcohol with a chemical). Some stations run 0% ethanol, some run E15 with 15% and some even run E30 with 30% alcohol (lots of stations here do the E30 in the summer and while the octane rating can be higher, you burn through it fast and many vehicles run quite a bit leaner).

This will directly affect mileage by a couple mpg.

[hp jnkey]

When I had the E60 535, it actually made better gas mileage with the Cobb than it did Stock.
Stock I was getting 25 highway and 28 with the Stage 1 Cobb tune.

Now with my F10 535 I have the JB4 Stage 2 and the gas mileage seems to be the same as stock.