Do the '91 and '92 9000 Turbos get the same fuel economy as the '86-89 9000 turbos, in people's experience? I'm asking about strictly highway cruising, not around town, preferably with manual transmission. Thanks!
Yes and no. My 97 Aero gets better fuel economy around town than the smaller engined 9000 T but slightly less efficient at highway speeds. This is what you'd expect from the bigger engine with more torque low down. The cars are very close in weight and drag.
The difference isn't enough to make a difference in buying either engine. In fact, the 2.3 is amazingly efficient compared to just about any other engine of its performance capabilities.
A '97 Aero gets worse highway fuel economy than an early 9000T? That's surprising to me, given the much different (taller) gearing on the Aero. I also was under the impression that the CS/E/Aero body style was more slippery aerodynamically, than the '86-92 body style, but I could be wrong.
Going by MSN Autos, I see the following EPA numbers. Does anyone know if these are accurate?
If these are accurate, the '91 is at a 3-4 MPG deficit on the highway compared to BOTH the Aero and the '86-90 turbos. That's a huge 10%. My '87 would get 29-31 cruising on the highway, depending on the speed limit. It just seems weird that Saab would have a model that's so much less efficient than previous models, does it not? Also, MSN says that the '91 has a 16.4 gallon tank, vs. 17.9 for '86-90 and 17.4 for '92-98. This has got to be an error. The body is the same as the early models, and there's no reason at all a '92 would be different from a '91 in fuel tank size?? Anyway... just rambling here. As you can guess, I am considering buying a '91 9000T. I know it will be a rocket, but with fuel prices as they are, don't want it to get worse highway economy than my brother's 7 passenger minivan.
These are for USA specification cars, so 1991 means the 2.3l. After 1990, there was no 2.0l 9000 in the USA. So you really only get 25 MPG on the highway with the cruise control set? I'd find that sad.
I generally get about 23-24mp (US) g commuting back and forth to work, and just about 30mpg on long distance highway cruises. I had formerly had an '87 9000 Turbo which got just about the same mileage, but on regular gas. Both were manual transmissions. These are real mileages from tank fill-ups - the trip computer generally overstates it by 10% or so.
I generally get about 23-24mp (US) g commuting back and forth to work, and just about 30mpg on long distance highway cruises. I had formerly had an '87 9000 Turbo which got just about the same mileage, but on regular gas. Both were manual transmissions. These are real mileages from tank fill-ups - the trip computer generally overstates it by 10% or so.
That's more in line with what I would expect. I am not too concerned with the mixed fuel economy, which will always be lower due to warm up times, starts and stops, etc. If it will do 30 MPG in steady state cruising on the highway, also about the same as my '87 9000T, that's good enough for me. It sounds as though you use premium gas in the '91? Does the manual actually recommend that, as on the Aero, or do you just find that it performs better? Thanks for the feedback.
These are for USA specification cars, so 1991 means the 2.3l. After 1990, there was no 2.0l 9000 in the USA. So you really only get 25 MPG on the highway with the cruise control set? I'd find that sad.
well, considering my cruise is removed, among other things... um, foot steady, speed steady, i can rake out about 28ish, but mind you my 9K is no longer stock...
well, considering my cruise is removed, among other things... um, foot steady, speed steady, i can rake out about 28ish, but mind you my 9K is no longer stock...
Well, my '87 was nowhere near stock either, having pulled 198 HP and 230-something torque at the wheels on a dyno. It didn't seem to affect the cruising fuel economy, though. Man, I could not live without cruise control now! My first car, which I owned for about six years, didn't have it. Now that I've been driving cars for the past 11+ years with cruise control, I never want to go without it again. I did have the A/C removed on my '87, but only because I was too cheap to get it repaired. Now though, A/C is another must have. I must be getting old...
28 MPG still isn't bad for having no crusie control and a ridiculously fast car. It's the 25 MPG figure that is troubling. I don't think I could deal with that. Can anyone comment on the fuel tank size in the 1991? Is it really 1.5 gallons less than the 1990?
Interesting point about the taller final drive on the 5 spd Aero, it is very noticable if you drive the two models back to back as I was able to do for the 6 years I had both types. Higher compression in the 2.3 than the older 2.0 liter engine as well. But you can't get away from the fact that the 2.3 liter engine displacement is 15% larger than the 2.0. There is a reasonably direct correlation between engine size and fuel consumption, all other things being equal. This is because the smaller engine works harder and spends more time with the throttle open than the bigger engine to achieve the same results. Diesel engines do not have this advantage as they are unthrottled so proper engine sizing for the application is essential to achieve ideal fuel consumption. Diesel has this substantial advantage over gasoline engines. This probably lead SAAB to explore an unthrottled gasoline engine, as well as other manufacturers including FIAT with their ingenious totally variable cam timing and lift system. The unthrottled spark ignition engine is the Holy Grail of fuel economy engineers. With FSI and fully variable valve timing coupled with SAAB's idea of using the piston head as one of the spark electrodes (yup, the compression ratio becomes the plug gap!). But I digress.
The 97 Aero is about 1 inch taller than the older cars, even though it is 3/4 inch lower than the standard late model 9000T. This is reflected in ground clearance since the older car has the same roof line exactly. The 97 Aero rides on 205/55x16 tires which are taller than the 195/60x15 stock size on 1988 and earlier 9000T (actually the 87 used 205/55x15 which are atad shorter yet but the ride and steering weren't as good so SAAB went back to 60 series and then later to 65 series 15 inch tires). So, ironically the lowered Aero chassis actually rides higher than the standard 86-90 model (I had both models side by side in my garage and measured the actual heights with a tape some time ago). The ride height of the standard later model is over one inch higher than the older bodyshell.
I doubt the total drag for the bigger bodyshell (longer nose, higher tail) would be less than for the older bodyshell as total drag is a function of the coefficient and the frontal area presented (by definition since drag coefficient is drag experienced as a fraction of drag of a flat plate of the same total cross sectional area). Although the geometric frontal area would be the same, for practical purposes the slightly higher ride height of later cars would "present" an effective frontal area slightly larger for the later cars.
So, my actual experience (not the EPA fake test) confirms my suspicion that the bigger engine would do better around town (less time spent accelerating the mass, more time trundling around with very little throttle) than the older engine but the highway mileage would be slightly inferior especially at higher speeds. The highway efficiency would result from the smaller engine working at a more efficient combination of throttle opening and boost pressure than the lower revving but higher boosting bigger engine.
Turbo engines act like variable displacement/variable compression ratio engines (possibly why SAAB explored just such a concept with high pressure mechanical supercharging of a very small engine but with variable displacement, and got very good fuel economy results) so the normal rule of smaller engine always getting better fuel economy (due to lower pumping losses) does not necessarily apply. Keith Duckworth of Cosworth fame reckoned that a relatively slow revving lightly supercharged (turbo) large displacement engine would win F1 races over the high revving small engines if fuel consumption were the limiting rule rather than displacement.
In fact, the most interesting racing in the world would be a formula that required a minimum fixed weight of car of a fixed frontal area, (no wings of any kind) and with either open or closed body (as the fans prefer) but using any engine and transmission with the total energy content of the fuel measured and fixed for all competitors for any given race. This would put diesels back on the sidelines at Le Mans pretty quickly I should think!
The 97 Aero is about 1 inch taller than the older cars, even though it is 3/4 inch lower than the standard late model 9000T. This is reflected in ground clearance since the older car has the same roof line exactly. The 97 Aero rides on 205/55x16 tires which are taller than the 195/60x15 stock size on 1988 and earlier 9000T (actually the 87 used 205/55x15 which are atad shorter yet but the ride and steering weren't as good so SAAB went back to 60 series and then later to 65 series 15 inch tires). So, ironically the lowered Aero chassis actually rides higher than the standard 86-90 model (I had both models side by side in my garage and measured the actual heights with a tape some time ago). The ride height of the standard later model is over one inch higher than the older bodyshell.
I doubt the total drag for the bigger bodyshell (longer nose, higher tail) would be less than for the older bodyshell as total drag is a function of the coefficient and the frontal area presented (by definition since drag coefficient is drag experienced as a fraction of drag of a flat plate of the same total cross sectional area). Although the geometric frontal area would be the same, for practical purposes the slightly higher ride height of later cars would "present" an effective frontal area slightly larger for the later cars.
That's some very interesting information about the ride heights. By what you say, it seems that the '91-92 turbos should be the shortest of all? Don't they use lower springs than the '86-90, while having the smallest tire diameter of the early body styles (205/50/16 < 205/55/15 or 195/60/15)?
Just a little somethin i have noticed on my '86 9000T... When driving at 55-60 without cruise i seem to get around 28mpg according to the car's computer. However, with cruise, at the same, the computer says i get about 32-34mpg.
I dont know how accurate this is, but i just thought i would mention it.
btw, car is stock, if it matters.
Well, my '87 was nowhere near stock either, having pulled 198 HP and 230-something torque at the wheels on a dyno. It didn't seem to affect the cruising fuel economy, though. Man, I could not live without cruise control now! My first car, which I owned for about six years, didn't have it. Now that I've been driving cars for the past 11+ years with cruise control, I never want to go without it again. I did have the A/C removed on my '87, but only because I was too cheap to get it repaired. Now though, A/C is another must have. I must be getting old...
28 MPG still isn't bad for having no crusie control and a ridiculously fast car. It's the 25 MPG figure that is troubling. I don't think I could deal with that. Can anyone comment on the fuel tank size in the 1991? Is it really 1.5 gallons less than the 1990?
yeah, not being stock is great. I'm around 270bhp and no idea for torque. I don't really miss cruise that much as I never had it .. Once or twice a year i make the trip from school in FL, to home in NY and that's 20 hours straight drivign no cruise:/ not too bad, occassionally i wish i had it though.
yeah, not being stock is great. I'm around 270bhp and no idea for torque. I don't really miss cruise that much as I never had it .. Once or twice a year i make the trip from school in FL, to home in NY and that's 20 hours straight drivign no cruise:/ not too bad, occassionally i wish i had it though.
If you've upped the HP to 270, the torque is probably off the chart! I think stock torque is what, 238 ft-lbs or something? You must be well over 300 ft-lbs now, crazy!
One does tend to not miss things that they never had. Another example would be automatic climate control. When I got a new car about a year and a half ago, one of the things that seriously swayed my decision was automatic climate control. Having used it for 10 years in my old 9000, I didn't want to go back to manual controls. The bad part is that my new car has a much more elegant and simple automatic setup than the 9000, particularly compared to the ACC2 in '90 and newer. But, I think I can deal.
Cool, thanks! If the Aero can get 5-6 MPG better than it's rating at the speed limit, I would guess that the '91 probably does as well, or at least by a few MPG. This has always been my experience with cars, glad to see that it's still the case with the 2.3l 9000T. In any case, I should be finding out this weekend!
Better fuel economy when operating cruise might be due to the constant but almost imperceptable movement of the gas pedal when driving "manually". This uses more fuel but car speed variation is so tiny you think you have your foot steady on the pedal. Some electronic throttle software corrects for this by essentially applying fuzzy logic to the pedal movements to decide if more power is actually being called for or you just moved your foot when the car went over a small bump!
I picked up my '91 9000T yesteday. The manual does indeed specify 16.4 gallons as the tank capacity, bummer that. However, at least by EDU, fuel economy is definitely better than MSN's reported 25 MPG. I got 31 MPG on the way to work today, and that includes engine warm up. EDU said about 28 MPG coming home yesterday, with an outside temperature around 15 degrees F. Works for me, but of course I will continue to keep records and see how it goes. The car has snow tires on at the moment too, which may affect economy (?).
Snows definitely use more fuel. 5 to 10% more depending upon carcass and tread design. Big lug treads eat gas, neater more modern treads are similar to summer tires. Cheaper snow tires are particularly bad as guzzlers as good carcass design costs lots of money.
Oh, I also didn't realize until yesterday, that the snows are 205/55/16, about 3.3% larger diameter/circumference than stock. So, that means the car is going about 3.3% more distance than the EDU thinks, as the EDU calculates MPG based on the stock tire circumference. Right?
Oh, I also didn't realize until yesterday, that the snows are 205/55/16, about 3.3% larger diameter/circumference than stock. So, that means the car is going about 3.3% more distance than the EDU thinks, as the EDU calculates MPG based on the stock tire circumference. Right?
i think that since your engine has to work harder to turn larger tires (less mechanical advantage), it pretty much cancels out any gains becuase the gains would be so small...
i think that since your engine has to work harder to turn larger tires (less mechanical advantage), it pretty much cancels out any gains becuase the gains would be so small...
Sorry, I wasn't clear before. I didn't mean to imply that the car would be getting better fuel economy with taller tires. I only meant to say that the EDU would be reporting lower mileage than what the car was actually getting, because of the tire diameter change.
Yes, works backwards from what might seem to be the case since the car actually travels further than the odometer reads. The ECU calculates on the basis of wheel revs so figures your fuel consumption has increased since it cannot "know" that you have actually travelled further than the odo indicates.
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