I am trying to find ways to stretch a few more MPG out of my 2002 A4 1.8t MT. I Have a 200 mile daily round trip commute, and with gas going back up, I want to maximize the performance and savings. Since I cleaned out the air filter pre-screen filter it does seem to be getting a little better economy, but I know this car can do even better. I am thinking seriously about picking up a K&N drop in on my way home tonite, and I do have and exhaust leak at the Y before the resonator. My question for the long time Audiphiles is would I gain anything by replacing the pipe section from the flex joint to the resonators with a bigger ID? I figure where it splits, it does not seem to decrease in size so the cheapest way to open it up is to replace that section (with 4 kids, there is not a lot of spare cash for new cat back). Any opinions on what that will do for my MPG if I do not start really putting my foot into it. I was also thinking about the APR ECU flash. Does anyone have any real world fuel saving experience with it? It does make sense that if the engine has more HP then it will not work as hard to maintain HWY speed and therefore be more fuel efficient. With a little bit of data to support the savings, I can do a cost analysis and show my wife it will give a return in savings to do it and have a nice performance machine.

 

The jury's been out for decades on whether a K&N drop in can help economy or not...odds are if it does you're talking about less than a tenth of a MPG. Keep your tires properly inflated, take out as much weight as you can reasonably, keep the car tuned up and drive conservatively are your best bets.

 

The K&N did nothing for my A6 and I've tracked actual mileage for years. I did not notice any difference with the chip since it only kicks in during hard acceleration above 3000 rpm. If you do a lot of that, say goodbye to fuel economy. Keep in mind the added boost is pushing air/fuel into the engine faster, not exactly a recipe for fuel efficiency. Best advice is tire inflation and drive conservatively, coasting up to lights and stops where possible.

 

x3 on tire inflation, rotations, and alignment. maybe take out the spare, if you have AAA to help you just in case. The rear seats weigh alot so taking them out would help, but you would get road noise from the trunk. Like also stated, just drive conservatively and don't flash the car

 

Man you guys are no fun, in the last line, I am looking for data to convince my wife it is a good idea to up my performance for fuel savings. I did actually hear back from the APR R&D folks, and they say that their research shows a 2-3 MPG improvement with the flash and conservative driving IF you can keep you foot out of it. Considering most of the time I am in line and stuck behind others moving at a steady pace, and when I am close to home in the rural areas I tend to coast frequently, I do think I can control myself.

 

Cost of the flash? What kind of economy are you getting now?

I don't want to be a wet blanket, but 2-3mpg is going take a long time to recover a couple hundred bucks for a flash...justifying performance mod $ to your wife as a fuel economy is probably a bad tactic...you're gonna get busted and spend alot of time on the couch.

On the other hand, you're going through a tank of gas daily so your return on investment might actually happen in a reasonable time.

Most people in your situation opt to buy a tercel or something that gets 40-50mpg and call it a day...save the nice car for the weekends when you're not stuck in traffic.

 

i think the K&N is a gimmick. even if it does improve air flow, it's at the cost of filtration efficiency. i've heard some people get better milage with a stage 1 chip compared to stock. and i agree with tdoyle, the cost vs return in investment could take years.

 

Well, let's do the math on it. APR stage 1 is $500. He's got a 200 mile per day commute, so that's 1000 miles/week if it's a 5 day/week thing.

If we assume 27 MPG as a baseline, 1000/27 = 37 gallons/week * ~ $3/gallon = $111/week in gas.

If he gets +3 MPG = 30 MPG from the stage 1, he'd see 1000/30 = 33.333 gallons/week * $3/gallon = $100/week in gas.

$500/($11/week) = 45 weeks, or slightly under 1 year, to break even.

Obviously I'm just throwing example numbers out there, but even if he's getting 30 MPG to begin with and the chip only gets him to 32 and gas drops to $2.50/gallon, he'd probably still break even in under 2 years.

It's not a fast return on investment, but it's not exactly gloom and doom either. That said, a cheap little car that just gets better mileage to begin with is probably a better long-term proposition, especially given that such a vehicle will probably run happily on 87 octane rather than the 91+ that our cars need, thus saving roughly 20 cents/gallon.

 

kudos

 

Now lets also consider that we are rapidly approaching the beginning of the Summer travel season, and we will be coming out of the discounted gas prices into the predicted $4.00 a gallon prices they are expecting this Summer. Given the math and yes 27MPG is a fair baseline for my experience, this could mean a quicker payoff.
1000/27 = 37 gallons/week * ~ $4/gallon = $148/week in gas.
1000/30 = 33.333 gallons/week * $4/gallon = $132/week in gas.

$500/($16/week) = 32 weeks, or slightly over 6 months, to break even.
Yeah, it is taking the extreme of their predictions, but since they have pushed it up that high before for no real reason other than to take more profits, it is not unrealistic. So given my commute it is realistic to say that somewhere between 6-10 months is not a bad return. The other part is that may go up with the new exhaust that I have already shown will be cheaper to upgrade than replace with stock.
Either way, it is time to start keeping track with an Excel spreadsheet. Data can win the arguement.