04 bmw 330 efficiency training

[tylerc]

So I recently got a new job where I will be driving a LOT. I have an 04 330ci BMW and was thinking about garaging it and getting an old civic for some good mpg when the better half gave me the old "if you get another car your sleeping in it"

Now I am looking for ways to improve the mpg of the car while still retaining the looks and performance of the car I love.

Right now I am getting a (horrible compared to you guys) highway mpg of about 26mpg at 70-75.

Currently I have a http://namotorwerks.com/images/vorst...trunk_lid3.jpg csl trunk with integrated spoiler installed which I think is equivalent to a Guernsey flap. What people have told me is that this is one of the few mods that makes your car more slippery and also provides down force. Any opinions?

I also have a different front end on the car which is lower then the stock piece but also has a small diffuser like this:E46 front bumpers image by kraycoenterprise on Photobucket is this good or bad for mpg?

I have on order a set of underdrive pulleys which should increase mpg and power, I will report back what I find with those modifications.

I also ordered a set of vortex generators and wanted some opinions on both how effective they would be and what people thought on the looks. These aren't attached and I am trying to figure out if I should or not. I am really torn over this because originally I really didn't like how they looked. after I painted them and stared at them a while I didn't mind them but would like some more opinions.






Thanks, any other suggestions would be welcomed!

[COcyclist]

tylerc, Welcome, nice Beemer! The trunk lip probably is OK for reducing drag. The vortex generators usually get poor press on this site. The front bumper cover looks good to me, especially if you can block off/smooth the fog light holes because it does seem to cover the front tires a little more. Honestly, the biggest mileage gains will come from changing your driving habits. It's not flashy or macho but that is where you will see the biggest gains and it costs very little. If you are serious about better mileage and you don't have a trip computer with instant mpg, get a Scanguage II. It plugs right into the OBD II port and will show you where you waste fuel and where you can save. Once you have accurate temperature readings from the Scanguage you can do an upper grill block, inflate tires to max and coast in neutral when possible. Read all the tips on this site. If most of your commute is highway, you want to improve aerodynamics and/or slow down.

[COcyclist]

I drove a friend's 325xi last week. Sweet ride but it was an automatic. A manual is better for hypermiling. You asked for an opinion on vortex generators- personally, I don't like the looks and they may not help, despite the manufacturer's claims. The roof line has a nice curve and is very smooth. I wouldn't do anything to disrupt the airflow. Just my 2¢.

[bandit86]

my brother has a 08 323 with the 2.8L engine, his speedo is out a bit, shows 110 at 105km, but his mileage frequently drops to 5.5L on the highway. amazing compared to my old 325IS with the 2.5L

I was thinking about getting a late 90s bmw and seeing what I can get out of it

[AeroModder]

Vortex generators are far more effective at reducing rear lift than drag. You may see a few points taken off your Cd, but it won't show any returns at the pump. You will notice your rear end will feel more planted in high-speed corners, though.

Many newer BMWs have a single fin on the rear, which I believe is an antenna:


These also act as vortex generators, and should help the airflow remain attached on the back glass. Tuft testing is a quick and easy way to see where the problem areas are, and what improvements your modifications will do. But if you do decide to put the set of 10 fins on, I recommend placing them along the edge of the rear window. For the angles, I'd put them at (in order from the center to the sides): 15, 10, 5, 5, and 0 degrees.


Since you have a more popular sports car, I highly recommend looking into the racing equipment catalogs and ordering a full undertray. Cleaning up the underside definitely gives you an improvement.

[SentraSE-R]

In two words, slow down. My SE-R gets 26 mpg @ 72 mph. It gets 33 mpg @ 62 mph, and 38 mpg @ 55 mph.

[jkp1187]

Originally Posted by SentraSE-R

In two words, slow down. My SE-R gets 26 mpg @ 72 mph. It gets 33 mpg @ 62 mph, and 38 mpg @ 55 mph.

Agreed. And also consider not just top speed but how fast you're accelerating to get up to speed -- that's where you're probably burning a lot of fuel. I have a 135i with an automatic -- it has an EPA highway rating of 25 MPG. Your car is rated at 27 MPG highway (per the new EPA system.) I can easily get 30 MPG highway if I'm being reasonable about the throttle and crusing at 65 MPH. On a trip from South Carolina to Pennsylvania, I was able to get 28 MPG despite driving up and down hills, and having a max speed in the 90's. (Kids: don't speed.) Remember - that's what I've managed with twin turbos and an automatic, so your naturally-aspirated 6 should be able to do better than that. So you might benefit from 'tuning the nut behind the wheel' in terms of driving style more than mods.....

Since you have an '04 Bimmer and are planning on doing a lot of driving with it, I recommend that you e-mail Mike Miller, the tech columnist for Roundel and Bimmer and ask that he forward to you his 'recommended' maintenance schedule. He can be reached at tech talk @ roundel. org.