Turbocharged Saab hit 99.9 Mpg highway, 51 Avg after fill.

[Frank Lee]

What exactly do you teach?

I find one-run fe claims hilarious.

What do they mean?

See "Sport Coupe" as exhibit A. Coupe's numbers are not fake... but you can be damn sure the whole gaslog average fe is nowhere near that of the particular "snapshot" I have here, for the reasons you derisively listed above and even more.

[euromodder]

Nice result !

Originally Posted by Drive Stick

The vehicles mpg calculation is not an instant reading, it doesn't fluctuate quickly at all, it climbs very slowly.

They either give instant FC, or a tank average FC.
Then again, even instant FC is usually slowed down slightly - by a few seconds - to keep it from changing constantly.

The Scangauge reading is closer to being instantly, it's at 0 L/HK some 5 seconds before my car's FC reading goes to 0.

[Drive Stick]

Thank you to those in support of great gas mileage, I appreciate it. The cars gauge does tank AVG, which is why it was shocking to see it reach 99.9 but that was after back to back to back downhill coasting engine off.

I was excited about the fact that I was finally able to see the driving habits at work with this car. My other vehicles don't have any such OEM equipment to help me read things. (also installed aftermarket vacuum/boost gauge in this one.)

Everyone gets "unlimited" gas mileage when coasting with the engine off, and most of us get in the 20's / 30's around town so I don't know why it's hard to believe that some of the time we are actually getting 99.9mpg. That's how the overall tank numbers raise significantly, by having high highs, and not so low lows. Everyone's car does this under the right conditions.

Frank Lee - people don't make posts about every tank they get good results from. They post when they get outstanding results, or something note worthy to encourage the fellow board members. I want people to know anything is possible. I can see why you might say:

Originally Posted by Frank Lee

I find one-run fe claims hilarious.

because quite Frank-Lee... it's funny how people drive long distances remaining on the gas pedal the entire time. They could be using advanced driving techniques and reaping the benefits of saving some at the pump.

[320touring]

I feel I should comment on this thread..

I've just bought a saab similar to the one the OP is discussing.

A couple of observations/points to make

1. The SID (onboard computer) offers BOTH Average and instant MPG

2. Even the 185bhp engines have a compression ratio of 8.8:1 (not particularly low for a turbo engine, infact similar to the m20 6pot 12v NA lump in my old BMW's)

3.I dont believe the OP is claiming that his FE figure is representative-merely reporting his findings on this ONE trip.

4. I'm currently baselining my car, and hope to have a figure available within the next week- currently its looking like 40mpg UK (33mpg US) with no EOC.

Certainly, its worth taking all figures published with a pinch of salt, but there will never be a shift in attitude of the general public if us ecomodders cant support each other!

Thankfully the OP is not selling a "Snake oil" additive etc.

[RobertSmalls]

Originally Posted by Old Mechanic

I believe his figures are possible...

They are possible in that car, but not at 65mph average. At 65mph, it takes far more energy per mile to drive a Saab through the air.

Using P&G, operating the engine near peak BSFC or not at all, I was able to achieve almost 50mpg in my Subaru Legacy on ideal terrain - at 35mph.

DriveStick - the techniques you use do save fuel, and your Saab has pretty good aerodynamics. I'm sure you got pretty good mileage, but I would expect something in the low 30's with cruise control, low 40's with the P&G that you used. I have to admit a lightened Saab is better configured for this sort of driving than I had realized, for the reasons OldMechanic mentioned.

Fuel pumps are known to deliver inconsistent fills (just ask anyone at a fuel economy run), and extraordinary claims require extraordinarily careful data gathering.

So for now, congratulations on what is in any case an impressive result. Now let's wait and see if your next fill comes up long.

[Wonderboy]

Originally Posted by autoteach

I do find it hilarious when someone tells of success that there are 10 people waiting in line to tell him that he mis-filled his car, that he had wind at his back, he didn't do aba testing, the 3 or more tanks that he filled were all short? and didn't give true results. It is quite frustrating. If he is in a hilly or mountainous terrain, getting double the EPA rating is fairly easy. Plenty of people are getting 25-30% better on flat terrain. Believe what you want, but you don't need to always call BS to feel important.

I believe you are misreading the sentiment here. The "naysayers" as you would have them are known, reputable, frequent posters. They (we) are here not just to pat each other on the back, but to make sure everything we do that for is replicable and worth that pat. Having been around here for a while, I would encourage you to trust that RobertSmalls, Daox, Frank Lee, et al are KNOWsayers, not naysayers... plus a little bit of venom as always from Frank .

I'd be willing to believe this number is achievable with this car, because it does have reasonably good aero, but I doubt you could keep doing this trip. I also believe you had ideal conditions for this tank. My friend has an 01 9-3, which I would consider VERY similar to your car. I have driven this car. I do well in fuel economy competitions if I might say so, and getting this kind of mileage from a saab like yours is tiresome without mods, and I would add doubtful at the speeds you mentioned - as you said, it's much easier to coast in slower speeds. Like I said, I don't not believe you, but I too think you had some pretty ideal conditions, and doubt the duplicability of this tank. Aerodynamic modifications would help not only your time at the track, but the ease of consistently getting numbers in the 50s. Although it's exciting to get a one-off tank with very good numbers, I feel that's not what we're really after here. I think the real purpose behind the forum is CONSISTENTLY good mileage; reporting whatever mods/techniques used for others to try out and keep pushing the MPG envelope. Don't take it as us shooting you down, take it as encouragement to continue testing and give a good solid raising of the bar for other saab owners to aspire to and try to get even better.

[Drive Stick]

No doubt about it, some areo mods would keep figures like this possible on long trips. The conditions were perfect, no traffic, no wind, no obstacles, and a LOT of huge hills. Up-hill climbs were in the 50-55 mph range, and steady flat driving was 61-63. Downhill coasts obtained speed which I can not mention. The momentum kept me going much further than if I had used the brakes and maintained a legal speed limit down hills.

(I do not condone breaking laws, as always with no risk there is no reward.)

Getting this kinda mpg from this vehicle (or any) is only possible under the same circumstances. That much is certainly true. Results will always vary, to what degree I don't know. I will definitely record my results next time I go upstate and back to compare.

Next time I go, I will probably have more hp and more weight reduction - but don't let that confuse you. Results only depend on how the vehicle is driven and the outside conditions.

[wdb]

Originally Posted by Drive Stick

Downhill coasts obtained speed which I can not mention.

Ya think? Nice numbers, thanks for sharing them. I want to move where the roads are that uncongested!

[Frank Lee]

Originally Posted by Drive Stick

Frank Lee - people don't make posts about every tank they get good results from. They post when they get outstanding results, or something note worthy to encourage the fellow board members. I want people to know anything is possible. I can see why you might say: because quite Frank-Lee... it's funny how people drive long distances remaining on the gas pedal the entire time. They could be using advanced driving techniques and reaping the benefits of saving some at the pump.

Note that I didn't go after the OP...

[euromodder]

Originally Posted by Drive Stick

Everyone gets "unlimited" gas mileage when coasting with the engine off, and most of us get in the 20's / 30's around town so I don't know why it's hard to believe that some of the time we are actually getting 99.9mpg.

On an instant reading, surely, but not on a tank average reading.

While coasting engine-off, metric format is a better indicator as it'd show 0 L/100 km.
But when stopped, it should read infinite ...
MPG is quite the opposite, it'd show an infinite reading during coasting, with 0mpg while stopped.

Neither of the infinite values can be used to calculate averages ...

That's how the overall tank numbers raise significantly, by having high highs, and not so low lows.

It's also the theory behing P+G .

Let's say you were getting 50mpg before starting the coastdown.
You'd need to travel an equally long distance with the engine off to reach 100mpg - and more coasting downhill to go beyond it.


Maybe the trip computer is using some very high (near-infinite) instant mpg values while you're coasting engine-off , and these may throw off the overall average reading ...

Technically it's correct to use the extremely high mpg figures, but in the real world it doesn't work out that way in the end