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how you diet your brick...???

^^^ and running deflated tires absorb bumps in the road which means you'll be driving straight forward rather than wasting gas driving up & down, reducing total number of miles that you have to drive
 
thanks for relaxing answers.....:rofl::rofl::rofl:

under the rear spoiler, i check the level of it. it seems higher than final drive, so for 944 should benefit but not as much.

my rode to work can't reach 120 km/hr, so aero load in not so critical, and i think is volvo quite a good student on the aerodynamic classroom.:rofl::rofl::rofl:

weight.. weight... and weight...
pleasessss......:oogle::oogle::oogle:

Aero and rolling resistance plays a huge role..
When I drive the brand new 208 at 50kph and put it in neutral and let it roll it'll drive much further than my old Volvo. The Volvo is heavier, it should have more inertia right...
Y know, y can gain quite some weight by replacing parts but it'll cost much more. You'll run out of things to remove before you notice any significant gains.
You'll lose quite some comfort and ease of use... If you want a lighter car get a smaller car. Volvos are heavy, deal with it. Well, not that heavy compared to brand new SUVs. Yet these still have a better milage.
Stop being so stuck on the weight thing 😂
 
Do some studying on this link.
https://ecomodder.com/forum/tool-aero-rolling-resistance.php

At just 64 km/h (40mph), your Cd=0.35 940 sedan could be fighting over 50% aero forces.

Think of it this way. Your rolling drag is linear with weight & speed, whereas your aero drag is squared with speed.

:nono: Rolling drag is linear with weight only. If your tire pressure is very low or you are driving on dirt or are in gear, then there may be some correlation with speed, but it’s unlikely that the relationship is linear.
 
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:nono: Rolling drag is linear with weight only. If your tire pressure is very low or you are driving on dirt or are in gear, then there may be some correlation with speed, but it?s unlikely that the relationship is linear.

Yup but if your car is in top shape (correct tire pressure, no useless drag from brakes or bad bearings ect...) Then drag becomes really important. That's what we are trying to explain to OP, along with "reducing weight wont get you much MPG wise unless you spend big bucks on it + you'll lose comfort" 😅
 
Take the space saver rims and put VW bug tires on them. They are 15x4.5 rims I believe. They fit on the front of stock 940's, clear the brakes. The VW tires are 15 inch and 155mm wide. Then air em up to 50lbs enjoy the free mileage. I do this for front runners at the drags course I put real drag slicks on the rear.
 
:nono: Rolling drag is linear with weight only. If your tire pressure is very low or you are driving on dirt or are in gear, then there may be some correlation with speed, but it?s unlikely that the relationship is linear.

Maybe in a textbook.

I real life it's not exactly linear (nothing is) but there are a lot of factors that do correlate with speed. And there's many different types of frictional effects/forces. There's unsurprisingly a whole field of study devoted to it (tribology)

While coasting at 60 mph, throw your car into a lower gear and see what that does to your rolling drag. You can even rev match before switching so that the rotational inertia does not play a factor, but yet, when you let off the gas and coast, you slow down at a much greater rate than when you were in a higher gear. You didn't change your weight of the car, and yet you increased your rolling drag.... If the friction of that component was speed-agnostic, then you would feel no effect by simply changing the engine speed and transmission gear (provided you compensated for the increased engine rotational inertia). The engine (which is mechanically linked to vehicle speed) has a higher overall friction force at higher speeds, due to fluid losses, pistons, crank, valvetrain, etc.

Granted, the relationship is not purely linear. It's a summation of all the frictional components in the drivetrain that would still drag if you were driving in a vacuum. Some of those elements are roughly constant, most (if not all) are non-linear, but show some correlation with speed, temperature, mechanical factors such as oil viscosity, tire choice, etc.
 
I would not drive such a heavy car on 155 wide tires. Not a daily driven car

Here is a trip I took with my VW sized tires on the space saver rims on the front of my old 740 hot rod daily runner.

<iframe width="560" height="315" src="https://www.youtube.com/embed/R5v6ellnpGU" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>
 
I would not drive such a heavy car on 155 wide tires. Not a daily driven car

:e-shrug: the vw bug tires sbabbs was talking about are 165r15 (165/80r15) I'm pretty sure. The same tires that the volvo 140s came with, and that didn't stop 145 drivers from hauling their stuff around.

My 165r15s are 86 load index fwiw
 
Remember its 16V Turbo guys, he can't be running around on super skinny tires. Lightweight rim and tire combo was a good suggestion, reducing unsprung weight is always good.

Approx 1 pound per inch is a nice ratio, so a 17" rim that weighs 17-18 lbs is ideal.
 
WoW, these are impressive Skinny tires. I think the quality of the tires plays a huge role.
I have 195 on my 240 and I feel safe that way, when you look at modern econobox and they have 200+ I'm like "there must be a reason"

Anyway, reducing unsprung weight is good but won't make huge improvements in milegage. OP seems kinda stuck on "losing weight" despite it NOT being the best way to get better milage, I call it quit.
 
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