MetroMPG's 1998 Chevrolet Metro (Pontiac Firefly) mods & repairs kitchen sink thread

[MetroMPG]

Hard to say without doing an A-B-A test, but...

Looking at past results for the same route in very similar weather conditions, I did a 160 km mostly highway round trip yesterday (90% secondary highway 50 mph / 80 kph PSL, 10% city) and got almost exactly the same 74 MPG on each trip. Driving style: DWL on the highway (when no cars behind) with the speed limit being my target speed. EOC in the city where appropriate.

But my average speed was 2.5 mph higher yesterday.

EDIT: AW CRUD. I just realized the comparison trip was before adding the lawn edging air dam. So it's a comparison involving two additional mods, not just lowering.

Debating whether & how to do an ABA test.

[iveyjh]

I like it, its just about the same height as mine and yes, the side skirts on mine makes it look lower

[MetroMPG]

^ I love the look of your car. Did you test the side skirts? Also prefer the look & location of your air dam.

---

Before & after...

[arcosine]

Hi,
Lets see, 74 mpg at 50 mph = 50 mpg at 74 mph. I'm thinking of getting a Geo metro and ecomodding it. Did you do the rear springs? Is 95 the best year?

The WAI on my saturn gets up to 175F at highway speeds, I use an old (80's) vacuum controlled flapper that opens to cool air at WOT.

I have a couple of spring compressors, you might rig something that holds the spring length and then jack up the car to get the springs out.

What springs did you use? I guess you 'll find out if it bounces first time you corner hard at speed. I made really stiff anti-roll bars on the saturn, slight oversteer without throttle. gets bouncy at speed and hard cornering, but zippy around town.

[Gasoline Fumes]

Originally Posted by MetroMPG

Debating whether & how to do an ABA test.

Clamp-style or rubber spring spacers could temporarily jack it back up to original ride height.

[MetroMPG]

Originally Posted by arcosine

Hi,
Lets see, 74 mpg at 50 mph

Not quite what it gets "at 50".

The 74 round trip number includes about 10% sub/urban driving, and my suburban numbers always pull up the average. The car as it is probably averages mid to upper 60's around 50 mph in nice, calm weather.

Did you do the rear springs? Is 95 the best year?

All 4 springs. Not sure what year is best, but I'd go for an OBD-II car just for the ease of plugging in MPG gauges.

What springs did you use?

I really have no idea! They're aftermarket, they're really old, and they are/used to be yellow, that's all I know. They came on the Swift GT parts car pictured a few posts back.

===

Fumes: good idea. I'm thinking I *will* ABA this at some point. It'll be good to know. I will remove the air dam to do the lowering ABA, because I'd also effectively be changing the air dam height during the test.

But I do plan on putting on a belly pan before doing the ABA. So, probably not until later in the summer. Just before I put the Miata on the road? We'll see.

[MetroMPG]

I drove the car again yesterday - pulling my light utility trailer to the dump... with my new trailer hitch! First productive use of that.

I'm getting used to the ride -- it doesn't seem as hard. (People can get used to anything, I suppose!) I am much more aware of potholes and bumps in the road, though.

The air dam, however, is NOT getting used to the new ride height. It's taking a lot of abuse.

[rmay635703]

Originally Posted by arcosine

Hi,
Lets see, 74 mpg at 50 mph = 50 mpg at 74 mph. I'm thinking of getting a Geo metro and ecomodding it. Did you do the rear springs? Is 95 the best year?

The WAI on my saturn gets up to 175F at highway speeds, I use an old (80's) vacuum controlled flapper that opens to cool air at WOT.

I have a couple of spring compressors, you might rig something that holds the spring length and then jack up the car to get the springs out.

What springs did you use? I guess you 'll find out if it bounces first time you corner hard at speed. I made really stiff anti-roll bars on the saturn, slight oversteer without throttle. gets bouncy at speed and hard cornering, but zippy around town.

Depends how you define best.

An 86 Chevy sprint with an 93 XFI motor would probably be the best FE wise
Stock 1993 XFI is the best for economy , other years are better at other things

[MetroMPG]

More data + observations on the lowered car after another short (200 km) trip (country back roads, as usual)...

1) I'm getting used to the springs. I only hit one bump that really made me wince. I tell myself this is what supercar drivers must endure, so it's OK. Because Firefly = supercar.

2) Driving over empty pop cans at 80 km/h is now a pretty dramatic event: It sounded/felt like it smashed, rattled and smacked along the full length of the underbody.

3) The air dam continues to suffer. I hit it on a low curb yesterday and knocked it almost completely off.

4) More data from a regularly driven route shows the lowering plus air dam making a noticeable difference: it was my fastest average speed recorded by 3 mph (9 round trips recorded), yet my MPG was 3 higher than a previous trip in very similar conditions. I spent the most ever time cruising at 80+ km/h / 50 mph at 70+ mpg. (Note, it's a net downhill trip by 37 m / 120 ft. over 100 km / 60 miles.)

[MPGeo]

Good to know that it seems your MPGs are higher with the lowered springs...