Just parked our new 1990 745 GL and our 1991 745 Turbo next to each other in the driveway. The 1991 Turbo is sitting with its front bumper one inch higher than the 1990. But the 1991's back bumper is sitting one inch lower than the 1990.

The only causes for this that I can think of are: that the 1991 has just over 3/4 tank of gas, the 1990 is below 1/4 tank; the 1991 has the third seat in the back, the 1990 does not; and the 1991 has a real spare tire in the spare well, the 1990 has a mickey-mouse (temp) spare (although the 1991's spare is on a Draco alloy wheel, which might lower its weight enough to equal the temp spare in the 1990).

Does this seem right for these two cars, or should I start looking at springs, etc.?

You'll go mad trying to figure out what/why. If it sags change the springs. I have 2 91 turbo wgns (740 & 940). I put new Scantech (no other option I could find)heavy duty wgn springs on my 740. Picked the ass end right up. 4 years later starting to sag again. People curse Scantech for a reason.
ian

700/900 cars suffer from endemic rear spring sag: the only way to solve it is with new springs. This can cause steering pull to right or left as well and is usually the first symptom you notice.
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See the 700/900 FAQ at the drop-down menu above right.

Steve, you are probably on to something there. Do the springs sag as a function of calendar age, or of mileage?

The car that is higher in the rear and lower in the front has relatively low mileage for a 1990: 103,000 miles. The one that is lower in the rear has around 300,000 miles on it, but is a year newer. It also has the job of hauling my three Great Danes (total = 410 lbs of Dog) to the veterinarian. That is a 250 mile round trip each time, so it racks up lots of miles with 410 lbs in the back, and usually a full fuel tank too.
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1955 Human, Scott; 1991 745 Turbo, Brunhilde; 1990 745GL, Snuggle Bunny

Almost entirely due to age.
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See the 700/900 FAQ at the drop-down menu above right.

Well, my tongue-in-cheek answer would be, "don’t park them so close together". In other words, it seems like you are just looking for trouble.

That being said, you do have about 120 lbs more in one than the other, so that might account for some of it. How do they ride, drive, and handle?

Charley

Hey, stance/ride height are fun to obsess over :|

Charley,

The 1991 Turbo seems a bit heavier in the wheel, yet more sports car like and, despite the higher nose, more hunkered down and clinging to the road. The 1990 GL, while handling very, very well, seems a bit lighter in the wheel, and less sports car like. Both handle very, very well and give great feedback and communication of road conditions.

There are tire differences too, but they should make the Turbo's nose sit a hair lower, not the other way around.

If you want to assess it, at the very least I think you should balance the weight between the two. I think the third seat can be removed in a few minutes and of course you can fill both tanks. Then, you can calculate in the tire radius difference and see how they compare.

If they are still off, take both to a truck scale that can weigh the axels independently and see what the weight difference is per axel. Then you could weight the lighter one to match the heavier one and see what you have.

After that, you can consider if you have an issue.

Charley