Suggested Aerodynamic Mods for a Cobalt
 

Hello all,

I never formally introduced myself, So i'll take care of that first. I'm a computer engineer from Canada. I first got into Hypermiling with a 2005 diesel smart car. I was averaging about 3.5L/ 100 km tanks, and had a best ever run of 2.7L/100 km on a 100km highway trip. My best tank was about 3.2L / 100km. I do a lot of highway driving, so aerodynamics are key. I do have my scanguage and rely on it.

The smart car gave me trouble, and i ended up selling it. I bought a 2007 Chevy Cobalt, 5 spd. (hey, when i bought it, it was dirt cheap). It actually does very well on the highway. I've managed a best ever run of 4.7L / 100km, and i'm averaging about 6.0L / 100km (i believe it's rated around 8.1L/100 km mixed city hwy)since i've owned it. However, i've hit an impass. I can't get better mileage without driving 70km/hr on the highway, NASCAR style drafting, or doing pulse and glide on the busiest truck route/highway in North America (Surprisingly, it's in canada... Who woulda thunk).

I'm planning on switching to synthetic oil and transmission fluid soon, and now i want to consider aerodynamic mods.

What does the collective wisdom of teh interwebs suggest?

Discuss.

-Steve

So, after lurking around some of the various threads here in the aerodynamics section, i think i can see clear to do a few things.

1) Smooth wheel covers.
2) Extend the air dam lower. There's actually a nice lip on the front of bumper my car i should be able to straight up bolt on a 5" wide strip of plastic. It's back a bit, and will be out of sight to!
3) Cover one of the grills. I'm thinking blocking the lower side grills would be easiest then, if temps remain ok, perhaps block the upper grill, leaving the lower center opening to provide cooling.

-Steve

Hello and welcome to EM.

I'd highly suggest taking a look at the 65+ efficiency mods at the top of the page. Thats pretty much our list of proven mods that help. They are also gauged by mechanical skill, impact, and cost. Find something you think would suit your daily commute and style of driving. :)

Your first few things are a good start. Generally its better to block the upper grill for aero.

Hi Steve,

Can you post some pictures? That would help us, I think, to give you specific suggestions.

As Daox said, check out the 65+ efficiency mods. You are bound to find a few in there that would be easy to do. The ScanGauge is a biggy, but you got that.

I noticed you posted your milage in Liters/Km. Aside from it being in metric, is it a Canadian thing to do Liters/Km versus Km/Liter (how we here in the states for Miles/Gallon)?

The most common SI/metric system for fuel efficiency is liters per 100 kilometers. Overall I like the unit more than miles per gallon because it makes planning trips around your fuel consumption a bit easier and doesn't seem to get as skewed out at low and high efficiencies as miles per gallon does. But I still use MPG out of...habit, culture, the speed limits and gas pumps are in miles and gallons...and no one uses gallons per 100 miles!

The majority of the civilized world uses L / 100km as it is the standard metric unit for fuel consumption. To quote wikipedia:

"As of 2008, all countries that used the imperial system have become officially metric, except for the United States, Burma and Liberia"

At least you have good company? Kinda? Where the hell IS burma anyways?

So, it's more of a 'rest of the world' thing, as opposed to a 'Canadian eh' thing. Up here, everything is in km's and I pay for fuel in litres. Plus miles per gallon gets really confusing because there is a us gallon at 3.8L and a proper imperial gallon at 4.5L. In Canada, if you use mpg you probably use the 4.5L gallon, and that just further confuses the issue! So i just stick to L/ 100 km. I guess i could also post in US gallons, as it seems to be a primarily US site? Gonna have to get my calculator out!

I understood why a Canadian used the metric system. But why L/100Km? Why not Km/L the metric equivalent to Miles Per Gallon?

I don't know. Perhaps because it's more intuitive that lower fuel consumption is matched with a lower number? In the scientific world, efficiency is always measured as consumable per unit work.

That's been discussed on here. Turns out, L/100 km or gallons/mile gives a more realistic way of comparing efficiency differences. For example, using mpg, going from 40mpg to 50mpg (25% increase) seems better than going from 20mpg to 25mpg (again, 25%). But the reality is 20mpg to 25mpg saves a lot more gas.