Finally reached hypermiller status :) - Fuel Economy, Hypermiling, EcoModding News and Forum

honestabe · 08-03-2010, 04:41 AM

I've only had my Geo Metro 15 weeks now and I think I've finally got my driving down good. Over my last 5 tanks I've averaged 50.3 MPG. Mind you 3 tanks ago I replaced a very bad passenger side axle (the CV joint was toast) and I replaced the trans fluid. I'm one of those people that drives a lot (as of my last fill-up, 520 miles per week on average) and I've put about 7900 miles on my Geo in the 15 weeks weeks I've owned it.

Doing the math, I've saved roughly 219 gallons of gas and $614 in gas compared to a 20 MPG car in just 15 weeks. That's $41 per week saved in gas

I really love my little Geo and can't wait to start doing some serious eco mods; partial camback, change back to the stock size tires (current tires are 175/70-13's and OEM is 155/80-13, which is about an inch narrower), change the trans fluid again to GM Syncromesh (running a notch thicker oil in the trans than OEM calls for), and pizza pan hubcaps (or moondisc hubcaps if I want to pony up $100 vs $20), 3tech cam gear and cam, and of course rear wheel skirts.

If possible I'd love to do the XFI trans conversion (I've seen it done before, just need to find the trans and cash).

Daox · 08-03-2010, 07:26 AM

Great work honestabe! 50 mpg is worlds better than 20 haha.

I'd rethink changing the tires though. I've been searching for tires myself and we share the same diameter tires. My Paseo uses 180/60R14 stock, but I have 155/80R13 on it right now and they need replacing. I've found there isn't much in the way of good tires left in the 155/80R13 size, but there are some LRRs at 175/70R13. I'm thinking of going that way, or possibly stepping up to a 14" wheel and new tires.

honestabe · 08-03-2010, 01:26 PM

Daox, the resistance difference between the 155/80 and 175/70 is significant. By my calculations, 4 175/70's are as wide as 5 155/80's. That's like driving around with a dual rear wheel setup on 1 side of the rear. And for someone who drives as much as I do, that's significant. IIRC I'm losing 3-5 MPG by having the 175/70 tires vs 155/80 tires.

wyatt · 08-03-2010, 02:45 PM

Quote:

Originally Posted by honestabe

Daox, the resistance difference between the 155/80 and 175/70 is significant. By my calculations, 4 175/70's are as wide as 5 155/80's. That's like driving around with a dual rear wheel setup on 1 side of the rear. And for someone who drives as much as I do, that's significant. IIRC I'm losing 3-5 MPG by having the 175/70 tires vs 155/80 tires.

First, it would be hard for me to believe that you are losing 3-5 mpg by having a slightly wider tire... it just doesn't make sense. The analogy that you use of 4 tires vs 5 may be correct if you only consider the width of the contact patch on the ground, but that does not take into account the ACTUAL overall width of the tire, plus what really matters is all the stuff that happens around the tire (air rushing into cavities and the like).
If you are serious about doing aero mods, you will undoubtedly eventually get around to shielding your tires with spats or fairings. These will negate the additional width of the tire, and the lower rolling resistance will take over. Actually, the lower rolling resistance will probably take over immediately, and be compounded by the aero improvements. Just make sure you get tires that have a good rolling resistance, either by getting LRR tires, or at least by getting 44psi tires vs 35psi ones. When I need new tires I am going with wider, 44psi ones, regardless of the aerodynamic implications... I will just get some lawn edging and shield the tires.

honestabe · 08-03-2010, 03:13 PM

Well I'm going to do some serious research and see what tires are best. My tires still have plenty of tread on them.

euromodder · 08-05-2010, 02:53 PM

What does it take to reach Hypermiler status ?
Seeing Daox' Prius numbers, even 19.8% above EPA ratings won't give that status.

wyatt · 08-05-2010, 02:59 PM

I believe that it is 20%... which would make Daox really close!

Arragonis · 08-05-2010, 03:37 PM

Congratulations on the status.

euromodder · 08-05-2010, 03:40 PM

Quote:

Originally Posted by wyatt

I believe that it is 20%... which would make Daox really close!

Oooch ...

My "EPA-rating" (well, rather Euro cycle average) is 47mpg or 5L/100km.
To do 20% better than that, I'd have to get 56.4 or 4.17L/100km , consistently.

That's pretty much uncharted territory for my make & model of car - predating Volvo's DrivE-programme

honestabe · 08-05-2010, 04:37 PM

Hypermiller status goes off of your last 90 days rating, which for me is 48.08 MPG, and 20% is the magic number.