mods that will improve fuel economy?

[splashz]

I just bought a used 135i convertible and I'm loving it so far. However I'm not getting great gas mileage. About 21mpg and I drive mostly highway (much of the time in traffic though). I'm considering bringing it in to a shop just to make sure everything is working efficiently.

Performance upgrades are nice but honestly, I'm pretty happy with the power of my car since I'm coming from a much less powerful car. I'd rather do something that will make my car more efficient and help with the gas mileage. Anything like that? I'm pretty new to modding cars but my buddy is into it and is willing to help me.

[igzekyativ]

remove the turbos..

[szcyxzh]

Originally Posted by igzekyativ

remove the turbos..

Life is short, enjoy every moment.

[splashz]

Don't get me wrong, I love the turbos and don't regret buying a fast car. Just wondering if there are ways to have my cake and eat it too.

[tcd223]

Originally Posted by splashz

Don't get me wrong, I love the turbos and don't regret buying a fast car. Just wondering if there are ways to have my cake and eat it too.

if you have the self control to hypermile a 135i, more power to you.

only thing I can think of is getting some really light 17" rims and if you are really serious, get some low rolling resistance tires.

[RimasRS]

Just buy M3 V8

oh my....

[Experimental]

Originally Posted by splashz

I just bought a used 135i convertible and I'm loving it so far. However I'm not getting great gas mileage. About 21mpg and I drive mostly highway (much of the time in traffic though). I'm considering bringing it in to a shop just to make sure everything is working efficiently.

Performance upgrades are nice but honestly, I'm pretty happy with the power of my car since I'm coming from a much less powerful car. I'd rather do something that will make my car more efficient and help with the gas mileage. Anything like that? I'm pretty new to modding cars but my buddy is into it and is willing to help me.

I asked the same question a few months ago, and the flaming began. Basically, there's not a whole lot you can do. Tires, keep the weight down (on the driver, as well as the number of things in your car), and your right foot will be your biggest factors. You can try going with carbon fiber parts like a hood and trunk lid, but the cost of those parts will far out-weigh the fuel savings. Possibly some lighter weight wheels...

Intake, exhaust, etc. aren't going to get you much on the 135i. Although, I'm curious to see how downpipes would affect fuel efficiency.

[evoq007]

Maybe its your driving? I live in boston too and get 25mpg every tank. I spend 40miles a day on I-93.

Auto or Manual transmission?

And yes i bring my car to redline multiple times a day

[ATSR]

As others have stated, the best mod that you can do to improve your mpg is your driving style.

[fourtailpipes]

some ideas...

behavioral:
-windows up, roof shut
-minimize in-car accessory use, like radio, AC, etc.
-draft trucks wherever possible (without tailgating of course... lets say to limit rock chips)

setup/aero:
-weight reduction
-narrower tires with higher pressure
-lower ride height
-wheel spacers
-consider a rear diffuser cutout to reduce turbulence/lift under the rear

[Allencic]

For a 135 I suspect your mileage is pretty typical.

In a long lifetime of driving I've had a number of good friends who complained about how lousy their mileage was. Without exception they all had several driving traits in common. First, they used the accelerator and brake pedals as on/off switches. Either full on or full off. Frankly, to ride with them was really unpleasant and often simply unsafe. Second, they never looked far ahead at the traffic so they could make smooth transitions in speed. An obvious red light ahead was usually met with a sudden, surprised need to stop quickly instead of smoothly. Third, their lack of situational awareness of the traffic around them often found them jammed in packs of cars going either too slow or fast, on and off the brakes and gas. Simply unpleasant, uneconomical driving style. Their jerky driving style often resulted in moving violation tickets. In short, they were crappy drivers.

[cenix]

it's possible to get mid 20's on highway only driving, but with lots of city driving, you'll see closer to 18 mpg or so. best way to keep mileage low is to drive easy, put car in neutral while idling at a light, and keep the tires inflated per spec. you said you have a convertible? i'm thinking your mileage may be a little lower on average than standard coupes due tos slight increased drag.

[splashz]

I drive in a style where I try to brake as infrequently as possible. I'm not going to pretend like I'm the world's most economical driver, but I'm also not slamming the gas/brakes at every light. But of course everyone says/thinks they're a good driver so take that for what it is...

[My135]

Disable 2 spark plugs and you should be able to improve the gas milage by approximately 30% :-):-):-)

[ken1137]

Originally Posted by RimasRS

Just buy M3 V8

oh my....

Heck with the M3...I say M5 V10...at least prior to the 2012 model

[mike the snake]

IF the car is driven correctly, won't the various tunes (JB4, Proceed, Cobb) available actually improve economy? I THINK I read about some people reporting slightly better mileage after installing their tunes.

[Vigilante375]

Originally Posted by fourtailpipes

some ideas...

behavioral:
-windows up, roof shut
-minimize in-car accessory use, like radio, AC, etc.
-draft trucks wherever possible (without tailgating of course... lets say to limit rock chips)

setup/aero:
-weight reduction
-narrower tires with higher pressure
-lower ride height
-wheel spacers
-consider a rear diffuser cutout to reduce turbulence/lift under the rear

I guess you dont watch Mythbusters huh? They proved, with a modern car, you get better gas mileage with the windows up and AC on. Plus drafting only works if you're like a couple of feet or less from the vehicle you're drafting to improve gas mileage. I really dont see how in-car accessory can affect your gas mileage.

Best and most effective way to help gas mileage is your right foot, dont use cruise unless you're on a FLAT road, going up hill will suck you gas mileage down while cruise is on, find the right speed where you're car gets the BEST MPG. I dont know where the sweet spot is for these cars but I know my GTO had the best MPG around 68-70 mph (about 25-27 MPG). Short shifting and skipping gears work too. I've driven cross country 4 times (WA to GA 2 times and GA to WA 2 times), so I know a few things. Getting 11 MPG in a 16 ft Uhaul fully loaded and towing a car on a trailer is hard to achieve.

If you let the engine breathe, you can get slightly better fuel economy. Not every car is the same but some work well with mods better than others.

[fboutlaw]

Possible impactors to fuel economy car related:
- Alignment
- Tire Pressure (higher and balanced L/R for better mileage)
- Weight
-- Store nothing in the car unneccessary
-- Lose some driver weight
-- Possible downsize your battery
-- CF panels, lightweight exhaust, flywheel etc.

Driver related
- Driving style
-- Drive smooth: easy corners and acceleration
- Driving route
-- Keep moving at highway speeds

Don't believe any mods that are one stop shops for xx.xx% fuel economy gain! The cake is a lie.

For reference, my average: 16.3 mpg due to all suburban driving, track/autox, mods.

[1speedbike]

New, more efficient intake (or drop-in filter for the stock intake)

Weight reduction- Race seats (lol), remove rear seats, lightweight battery, CF hood/trunk, lightweight 17" race wheels, lightweight eco tires, lightweight exhaust.

Aerodynamics- aero bumper/front lip, lower the car, make the underside more aerodynamic.

Reflash or piggyback car with custom tune/map to make it more efficient. Play with the boost and the air/fuel ratios. ONLY if you know what you're doing, of course.

[fourtailpipes]

Originally Posted by Vigilante375

I guess you dont watch Mythbusters huh? They proved, with a modern car, you get better gas mileage with the windows up and AC on.

actually i'm an avid mythbusters watcher. it sounds like you're misinterpreting their results. the windows/ac segment didn;t really "prove" anything, though it correctly demonstrated a concept: windows up and ac on may be better than windows down and ac off, but that's not relevant to my suggestion... i'm suggesting windows always up and limited AC whenever possible.

Originally Posted by Vigilante375

Plus drafting only works if you're like a couple of feet or less from the vehicle you're drafting to improve gas mileage.

if you look at their results, the draft showed improved gas mileage across the board, with better results the closer you follow (duh). they just ended it with some kind of statement like "but it only works if you're way too close" because they didn't want to draw a conclusion like "drafting can give you awesome gas mileage, especially if you tailgate the living sh!t out of the guy in front"

Originally Posted by Vigilante375

I really don't see how in-car accessory can affect your gas mileage.

all in-car accessories are driven by the engine, which burns additional gas depending on how much electricity is demanded by the accessories. therefore, they are essentially gas powered. this directly impairs fuel mileage.

[1speedbike]

Originally Posted by fourtailpipes

actually i'm an avid mythbusters watcher. it sounds like you're misinterpreting their results. the windows/ac segment didn;t really "prove" anything, though it correctly demonstrated a concept: windows up and ac on may be better than windows down and ac off, but that's not relevant to my suggestion... i'm suggesting windows always up and limited AC whenever possible.



if you look at their results, the draft showed improved gas mileage across the board, with better results the closer you follow (duh). they just ended it with some kind of statement like "but it only works if you're way too close" because they didn't want to draw a conclusion like "drafting can give you awesome gas mileage, especially if you tailgate the living sh!t out of the guy in front"



all in-car accessories are driven by the engine, which burns additional gas depending on how much electricity is demanded by the accessories. therefore, they are essentially gas powered. this directly impairs fuel mileage.

He speaks the truth!

[ptack]

You bought a relatively expensive 300 hp convertible and now you want to save a couple of bucks on gas? Did you think it was a Prius?