which mod gained most efficiency?

[Cd]

Originally Posted by Cd

I was the first to post on this question and had a list going until i re-read the question. If I understand right, the question is not how to get better FE, but whose modification has saved the most gas.

The first thing that comes to my mind is MetroMPG's alternator delete mod. , but I'm not sure if that falls outside the " non-daily drivable configuration ".

I guess i didn't understand right.

[Ladogaboy]

For me, driver and then LRR tires. To be fair, I haven't done a whole lot outside of that (basic aero mods and weight reduction).

[tinduck]

Mhhh... lets see..

1) Driving technique. Ohhh yes. I was trying to save fuel before I encountered this website by upshifting early, use low rpms, go slow etc. This was OK, but hypermiling techniques (coasting, P&G) gave me another approx. 10% increase in FE.

2) Tire pressure! I go 0,3 bar below max. sidewall pressure. For me, this is the compromise between FE and uneven tire wear. Cannot give FE improvement numbers for this, though.

3) My upper grill block seems to have given me around +5 mpg (48 => 53 mpg on my morning commute), though this is not A-B-A tested, just my trip data.

so long,

tinduck

[jime57]

(duplicate)

[jime57]

Originally Posted by tinduck

Mhhh... lets see..
2) Tire pressure! I go 0,3 bar below max. sidewall pressure. For me, this is the compromise between FE and uneven tire wear. Cannot give FE improvement numbers for this, though.

3) My upper grill block seems to have given me around +5 mpg (48 => 53 mpg on my morning commute), though this is not A-B-A tested, just my trip data.

so long,

tinduck

Go directly to max sidewall. The improvement up to that level is well documented and safe within the tire manufacturer's recommendation.

Not to be too critical, but your grill block outsized improvement of about 10% is not supported by A-B-A testing of others. Testing has shown improvements of the order of 3%, give or take a bit. Such testing usually starts with a well warmed car and drive train, otherwise you are testing two effects at the same time - warmup characteristics and aerodynamics. That said, fuel improvement is fuel improvement and a quicker warmup with less wasted fuel is still a genuine savings. Good savings, and good results.

You might achieve further improvement with some smooth wheel caps and some nicely designed and finished wheel spats. They are a good start down the ecomodding road.

Good econodriving

[kach22i]

1. Driving technique

2. Chin spoiler (was 14" now 7" clearance, would like to go to 3" in summer)

3. Cover on the pick-up truck bed.

[California98Civic]

It is a good idea to consider doing a dozen or so smaller mods generally known to help, even though their improvements are modest. Piled-up together you may see a larger improvement. But this is time-consuming. I find I generally have "temporary" versions of mods on the car as a way to get a feel for their function.

Originally Posted by kach22i

1. Driving technique

2. Chin spoiler (was 14" now 7" clearance, would like to go to 3" in summer)

3. Cover on the pick-up truck bed.

[ConnClark]

Actually getting your car chopped and channeled is the best aero clean up

[aerohead]

* on the VW bus it was the boat tail
* on the CRX it was the boat tail
*on the Dodge pickup it was the aeroshell
*on the Toyota pickup it was the aeroshell
*on the Toyota,the inflated boat tail also had a good showing along with a 1/2-tonneau and a storage container

[slowmover]

I would say tires, inflated properly. And that is from a certified weight scale and working with pressure versus load numbers; oem vehicle manufacturer and tire manufacturer numbers range. No way I can save enough fuel to offset prematurely wearing tires due to overinflation. Handling/braking issues aren't worth overinflation risks either. This takes things the wrong direction. My compromise is about plus ten percent over indicated load pressure, for now (80-psi tires). Much depends on how the truck is being used. As DISCOUNT TIRE has a nice COATES air pressure setup in their garages these days, changing pressures as much as 20-psi in the rear is quick (plus the air dryer system works).

As to genuine vehicle modifications -- and assuming adequate highway miles -- I look forward to grille blocks/winter front plus some undercarriage covers in the next year or so.

.