TMRoc

I just put a Borla Sports (Stringers) catbacks on my 05, C6, A4 with a 3.15 dif. My mileage drop to 17 mpg in the city and I just got back from a 500 mile round trip where the best I did was 23.3 mpg at 72 to 75mph… The only thing that I have done to the car was the catbacks. Prior to that for the last two years, I was getting 23 mpg city and 27 mpg on the hwy.
The change was made about a month ago. I have not had any codes pop-up. I have not contacted the shop that put the systems on for me yet. Does anyone have any idea what might be causing this problem?
Maybe it’s not a problem. I was thinking that after I put the exhaust on it may improve my mpg but, I never considered that much of a drop in MPG.

P.S. No I am not getting on it more or harder because of the sound.

'06 Quicksilver Z06

Hit the reset button while you have the AVG MPG on the DIC and ride around for a few days and see if you still get the same numbers.

TMRoc

Thanks, But that's the first thing I did.

mitchydkid

I don't mean to be non-helpfull, but....I will be.
A buddy of mine put flowmasters on his truck and his MPG dropped. After some head scratching he realized he was putting his foot into it more to hear the powerfull tones.

Just a thought.

-Dale

VET4LES

That's usually the problem. I have not noticed any difference after installing Zoomers.

TMRoc

Thanks, but, like i said in the 1st post I am not getting on it more or harder... But, Thanks for your help Anyway

don.donc

since you are not getting any codes, i will assume the engine is fine. that leaves the driver's right foot as the cause of the issue.

zare191

Unless there is some sort of internal blockage inside the Borla's, I can't imagine why that would happen. Does the exhaust pressure coming out of each side feel identical? I'd call Borla and ask them what might cause this problem. Good Luck!

0SicMSP - Daniel

Let the computer remap itself from the higher flow and check it in a week. you should be fine.

INGER67

Or it could be delayed shifting. I have an automatic and sometimes I just like to hear my Borlas. I start out in 2nd and "play" with the sound. My gas mileage isn't great if I do that too much!

Inger67

Painrace

I put Corsa Sports on my C6Z and my milage went down 2-3 MPG.

OOPS, maybe it was because of the additional 150 HP from Katech!

Bushong572

I've never seen 23 mpg in the city............17 is about normal from what I've seen.

jschindler

I've had several Corvettes with aftermarket exhausts, and never saw a decrease.

One thing that looks awfully suspicious is you saying you got 23 in town before. I'd like to know what your in-town driving consisted of. That would be awsome if it really is "city" driving.

Bushong572

I've never seen 23 mpg in the city............17 is about normal.

shopdog

Loud doesn't guarantee low restriction. The stock exhaust is remarkably low restriction, your aftermarket exhaust may not flow nearly as well. Driving with a restrictive exhaust hurts MPG and performance.

However, it is hard to believe that any aftermarket exhaust could be bad enough to impact your MPG as much as you say. I'm thinking that the mechanic screwed up something else while he was under there changing mufflers. Its hard to imagine what he could have done that would hurt MPG that much without throwing a code, though.

1bdasvt

iridelow

I put the Borla stingers on last week, and yes my MPG dropped, but only because my foot has gotten heavier due to the awesome sound....I am sorry, but I can't keep my foot out of the little gas peddle because I LOVE THE SOUND!!!!!!!!!!!!

mitchm11741

I am with you. My car is a stock M6 trans version. In the city (and I mean stopping at lights, 30 -40 mph, stop & go), I am running around 15-17 mpg. The best I see on the highway, with moderate hills and driving @ 60-65 is around 22 - 24 mpg (hills, tolls, moderate traffic). I have never seen > 20 mpg in the city unless, by some miracle, I can cruise at 40 mph without getting stuck at lights.

I don't know about you guys but ...

1. I drive very few miles in total so I don't give a darn about the mpg. It makes no big $$ difference in the big picture
2. I prefer to drive my car hard on occasion so I am not driving for optimized mpg

I doubt I will make a habit of checking my mpg ... I am just doing it now that the car is new.

opus1111

Don't have any insight for you, but I'll share my (vaguely related) experience: Mileage increased about 2mpg after installing my Vararam, Kooks headers and Corsas. Then my highway mileage dropped about 4mpg after retuning. Sure wouldn't go back tho.

I think it's ludicrous to try to compare city driving mileage from person to person, city to city, etc. Even the same person w/ same car on the same route will get a few mpg more/less if they hit the lights differently.

GotVett?

D.

Have to admit that I've been a little flustered with the mpg on mine also. Even before I put my Borla on I seemed to just get around 15 and change. No matter if I took it easy or not.

I also have had my Vararam for about 2 1/2 - 3 mos. now and really only noticed the SOP feeling once. But, that time was like my vette weighed only 1000 lbs with 800 hp. Anyway, I got to feel the way it is suppose to perform and I'll recheck things again on it.

I took your advice to the op and reset my DIC when I took it out just now for a check on my Valentine. Sure enough, the mpg's clicked right on up to about 19.6 before I had to get back onto my street.

The same thing happened about a month ago when I questioned my Vararam's performance. That's when I took the spacer off and the mpg readout climbed up again. WHAT AM I MISSING? Surely, you don't "reset" the DIC everytime you get in it, for the mpg to increase.

What's the deal? I don't get on it often at all, for that kind of poor mileage. Any thoughts?