Our 83 still knocks down 29-30MPG(US) on the highway at speeds averaging 60-65. Has about 165k on it now, and has done this since new. (Saw 33MPG occasionally in the old 55MPH days.)

Daughter's 940 is within 1MPG of this with the lockup converter on the automatic - something 240's never had. Her 4.10 axle ratio doesn't help!

A recent series of highway trips in the S90 yielded 29.8MPG overall, through the Cdn Rockies, averaging about 100km/h...62mph).

Even my 745 with the 5.7L V8 gets a hair under 26MPG on the highway at 65MPH! That engine has well over 100k mi.

Reports of B23/230 cars getting just 24-25MPG hwy puzzle me. Can non-lockup automatics be responsible for this 15-20% loss?

In common, all our cars have: Mobil-1 5W30 oil/new or clean air filters/proper wheel alignment/tires at 32-34psi/new or low mileage spark plugs/known good O2 sensors, etc.

As always, the main factor in fuel economy is your right foot!
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Bob (son's 81-244GL B21F-M46, dtr's 94-940 B230FD, my 83-244DL B23F-M46, 89-745(LT1 V8), 98-S90, 77MGB and four old motorcycles)