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mixadj 09-30-2012 06:45 PM

Improving 2008 Focus Sedan Aerodynamics
I regularly travel 120 miles every other week averaging 65 mph. I am looking at different ways to improve mpg. I currently run around 34mpg at 85mph and 36mpg at 75mph. I am planning to get a fswerks CAI for a bit of a boost, but have started to consider some kind of aero kit. I decided to try drafting on my trip today and found that I could get 38mpg as I was following a HD3500 at 80mph. This led me to ask, what kind of drag do these cars have stock and what can I do to help reduce the amount of drag at high speeds? Are there any beneficial aftermarket kits or will I have to do custom fab? I tried to find a previous thread for this and could not so I decided to start one. If anybody can impart some wisdom or point me in the right direction any help will be appreciated.

Oh yah, specs

Stock 2008 Ford Focus SES Sedan
2.0 Duratec w/ AR103 Plugs
87 Octane
Stock Wing (Does it actually do anything?)

WiscoGTI 09-30-2012 06:57 PM

You're complaining about 34mpg's in a 2008 Focus at 85mph? Really?

Sent from my Man Cannon via FF Mobile

GN Prime 09-30-2012 06:59 PM

can't help you on the aerodynamic question, but i will chime in on the fact that my mpg went down when i installed my cai. then got alittle bit worse when did my exhaust. its probably just me and not my car though:) don't forget to factor in a lowered suspension!
you could maybe give these a try:)

mixadj 09-30-2012 08:14 PM

@WiscoGTI I am not trying to complain or say those numbers are low.I am just trying to see how efficient I can make my vehicle.

@GN Prime Those actually look interesting, I will have to do some research. I searched for Vortex Generators and found one of your replies in another thread. Did you ever install them? I wonder what optimal placement would be.....

GN Prime 09-30-2012 08:35 PM

i never did install them:( i got the primed ones painted body color and wanted to go and actually figure out the true locations for them. but realized i was too lazy lol. i was doing it for appearance more or less personally. i still wasn't convinced that they would be that much of a game changer, since i don't do much highway driving and city streets only have so much distance to travel on:( but if you search on youtube there are a couple of how-tos on testing wind paths.

emsvitil 09-30-2012 09:15 PM

How smooth is the belly on a 2008?

i.e. Does it have a belly pan?

This may be your best bet, plus you don't have to worry about looks as it isn't seen............

Chaos09 10-01-2012 12:08 AM

Like emavitil said, get a belly pan and a rear diffuser. Lower the car and loose some weight. That should help some. Good luck

WiscoGTI 10-01-2012 02:47 AM


Originally Posted by mixadj (Post 4380831)
@WiscoGTI I am not trying to complain or say those numbers are low.I am just trying to see how efficient I can make my vehicle.

Then disregard my previous post. [cheers]

Paladin 10-01-2012 07:36 AM

best bet is swapping super low rolling resistance tires, a belly pan of some sort to smmoth out under aero as much as possible. significantly lowering the car (by 2 inches or more) and putting a rubber lip on the bottom of the front bumper to further cut down on air getting under the car. also may have to make functional fender vents and rear bumper vents to help get rid of the high pressure zone in the wheel well cause by the spinning tires

apart from downforce generating wings (which arent needed here) its basicly what people do for track cars.

IH84DZ 10-01-2012 08:12 AM

Buy skinniest, hardest tires you can find on some gramlite wheels. Strip down to race weight. Tape off every sharp edge and panel gap. Golf ball dimple the entire body. Accelerate as slow as possible

Arrow Dynamics

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