So, if anyone looks at the specs for the Fit... there's a stat for track width.

2007 Fit (and I assume for the rest of the GDs)

57.3" in front and 57.1" in the rear for both trims.

2010 Fits (again, assuming same for rest of GEs)

58.7"/58.1" for base and 58.1"/57.4 for the sport***

*** I have to assume that the track difference from base to sport is due to both the offset of the wheels and the width of the tires. Only makes sense to me if I think that Honda's measurement is from the inside of the tires, not the centerlines. And the difference of .6" for the base vs .7" for the sport is due to the person taking the measurement.

My question... what's the effects of the track width? And why are the rears narrower?

I've been thinking about this for a while... every time I get a little unstable feeling when driving on the highway. Did Honda choose a narrower rear axle to make it more biased towards turning ability and less towards straight line? this is just my thought ... mostly because I remember reading about the F-22 Raptor fighter jet. The design of the jet is to make it inherently UN-stable, so that it can perform all kinds of (crazy ass) moves, and relying on the computer to keep in stable otherwise.

Of course, that could be entirely wrong thinking. --> Vehicle Dynamics - Cause and Effect Guide - Trackpedia. They only mention possible effects of relatively narrower front tracks.

From what I could gather other sites through google... a relatively narrower rear track reduces oversteer. A couple of site actually say the opposite. hum...

I have said in a couple of threads that I'm planning on getting wider tires (205s) in the hopes of making the car a bit more stable in a straight line. some sections of the highway are bugging the hell out of me. I took a 4 hour drive last night after work at varying speeds... the instability doesn't always happen at a given speed. Some sections of road I'll feel it at 60 or 70, etc. other sections, I won't. I kept looking to see if it was windy, but the nearby trees didn't appear to be swaying in the wind (not like I could look at them for long). But, it mostly felt like the wheels are pulling me side to side, not wind pushing me.

I bring up track width because I know the 205s will affect the track width (again, assuming Honda used the insides of the tires, not centerlines).

 

I don’t know about Illinois, but out here on the Left Coast there’s a tendency to smooth out roads plagued by freeway hop by grinding them flat again. This often leaves some very slight longitudinal grooves in the concrete, that also tend to wiggle from side to side a bit.

I’ve noticed (with several cars, not just the Fit) that cars tend to dart/jerk slightly from side to side on these stretches – it’s like either the ribs of the tire tread can’t decide which of the grooves to follow, so they switch back & forth from one to another; or they’re trying to follow the grooves as they wiggle (or both).

So it might be the road surface that’s causing this behavior.

 

I've experienced that in San Diego. California "freeways" love the grooves.

While there are parts of the road that are ground down like you mentioned, I don't really feel anything there. But on some sections that appear to be smooth give the instability. And some (not all) bumpy sections too.

 

Yeah, I know about California grooved pavement, from when I lived in San Jose. This ain't the same.

It looks really smooth, unless you get some sunlight across it early or late in the day. Then you see these shallow fine grooves & ridges running down the concrete, like someone took a giant, heavy piece of really coarse sandpaper & dragged it behind their truck as they drove down the road.

There are several stretches of I-5 around here that make every vehicle I've driven or ridden in jerk from side to side almost like Harry Potter's broomstick in the first movie -- not that bad, and not unsafe, but definitely getting shoved around. You learn from experience that it's best to just gently guide the car down the road; don't try to fight it because that makes it worse.