1972 OLDSMOBILE Cutlass Supreme conv 350-4 bbl MPG= 10.5 Overall Print
Written by Double Dragon
Sunday, 23 April 2017 19:45

1972 OLDSMOBILE Cutlass Supreme convertible 350-4 barrel MPG= 10.5 Overall Average

oneownercollectorcar.com

Writing and photography copyright D. S. Brown

The Cutlass Supreme was conquering the family car market in the 1970s. Customers of the full size General Motors cars such as the Chevrolet Impala, Pontiac Catalina, Oldsmobile 88 or Buick Electra downsized to the cheaper, easier to park intermediate sized Cutlass Supreme. Notably, it was the Cutlass Supreme that received the lion's share of this downsizing trend partly due to the good reputation of the Oldsmobile 'Rocket engines' but in large part because the Supreme offered the same comfort level as a well appointed full size car.

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MPG FOR 1972 CUTLASS SUPREME WHEN NEW= 13.0 Overall Average

Sorting through the reports back in the day reveals a labyrinth of contradictions. The most accurate figures come from articles where the new car's performance was measured directly in regular use.

MOTOR TREND Nov 1971 tested a Cutlass Supreme two door hardtop with the 4 barrel 350 c.i. 180 HP engine, automatic transmission and 2.73:1 rear axle. MT observed that the Cutlass Supreme standard powertrain took the car to a top speed of 100 MPH. They didn't have the car long enough to test the MPG.

The book WORLD CARS 1972 compiles information provided by manufacturers; specs are calculated rather than observed directly. WC 1972 lists identical top speed and fuel mileage for the 350 cubic inch 180 HP engine standard in Cutlass Supremes despite two different available rear axle ratios listed in WC.

The Cutlass Supreme with 180 HP 350-4 barrel is credited with a top speed of 116 MPH and gas consumption of 13.0 MPG regardless of presence of 2.73:1 or 3.08:1 rear axle ratio. Its hard to know which rear axle was used by WC to calculate top speed. 116 MPH is much higher than the observed top speed MT achieved in their tests.

The salesman spec guide for 1972 states that the standard transmission and axle for the 350-4 barrel that was standard in the Cutlass Supreme was the M38 automatic paired to the 2.73:1 axle. The 3.08:1 and 3.23:1 were optional.

72 olds cutlass salesman specs powerteams

The figures quoted in WC for the General Motors 1972 'A body' intermediates vary wildly despite the cars using the same frames and similar body shapes and horsepower ratings.

WC states that the 1972 Buick Skylark with a 180 HP 350-4 barrel, 3 speed manual transmission, and 3.08:1 axle can hit 103 MPH.  Pontiac didn't have a 4 barrel 350 available in 1972. WC credits the Pontiac LeMans with 350-2 barrel (175 HP), 3 speed manual trans, and 2.56:1 axle at 111 MPH. The 1972 Chevelle with a 350-4 barrel (175 HP), 3 speed manual transmission, and 3.31:1 axle ratio was supposed to be able to run 112 MPH.

It seems the famous Rocket 350 Oldsmobile engine is best of all the engines according to WC with 116 MPH, but it could simply be that the different division engineers estimated the loss in top speed due to compression drop using different formulas. The WC book quotes figures using the manual 3 speed transmission. The salesman's guide shows axle ratios provided with the manual shift 3 speed transmission and the M38 TH350 automatic as seen below.

72 olds cutlass sales spec book engine list

WORLD CARS receives their performance figures from the manufacturer. The gas consumption WC comes up with is based on a moderately loaded Cutlass Supreme covering variable terrain at approximately 60% of top speed, which would be about 67 MPH.

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OOCC CUTLASS SUPREME DRIVING CONDITIONS:

The standard 1972 Cutlass Supreme 2 door convertible has a curb weight of 3,627 pounds according to WORLD CARS 1972. The Oldsmobile salesman's guide for 1972 states that the Cutlass Supreme convertible has a curb weight of 3,614 pounds (shipping weight of 3,510 pounds).

The 3,627 pounds quoted is technically correct but unrepresentative of the majority of Cutlass Supreme 2 door convertible cars built because the base car is listed with the lightweight 3 speed manual transmission in WC. Obviously a high end car like this convertible doesn't stand pat with the standard manual transmission, but listing a stripped car is a time honored tactic used to reduce the quoted base price.

The figures below are from the AMA stat sheet providing the weight of various options on a 1972 Pontiac. General Motors sourced their power steering, power brakes, A/C etc from the same suppliers regardless of the division installing the parts. The Pontiac accessory  figures apply to Oldsmobile, too. The weight for the radio comes from the 1967 Oldsmobile Cutlass AMA specs.

Below is a summary of the OOCC Cutlass Supreme options and the weight increase above the base 350 4 bbl manual transmission 'stripped' 2 door convertible:

+ 112.0 lbs- air conditioning              
+  29.0 lbs- power disc brakes             
+  28.6 lbs- dual exhaust            
+  28.0 lbs- power steering       
+  27.8 lbs- M38 TH350 transmission               
+    8.0 lbs- radio              
= 233.4 lbs added in total

The curb weight of the OOCC Cutlass Supreme totals 3,860 pounds plus a few more pounds for miscellaneous options such as the electric clock, bucket seats, console, dual custom sport mirrors with driver remote and so on. A realistic total would be about 3,880 pounds. Add 200 lbs for driver or miscelanious items and the as driven weight was around 4,080 pounds.

The standard tires on the Cutlass Supreme convertible were F78x14 with G70x14 and G78x14 optional. If the optional 455 was installed or if A/C was added to the 350 engine then the standard tire size bumped up to G78x14.

72 olds cutlass owner manual tire sizes

The owner's manual allows for a soft luxury ride with recommended light load pressures (up to 750 pounds) of 24 PSI front and rear. Heavier loads than 750 pounds required 26 PSI front and 28 PSI rear.

This Viking Blue OOCC 1972 Oldsmobile Cutlass Supreme convertible came up for sale in February, 2005 on a website that is now defunct named HotAutos dot com. This Cutlass Supreme has a 350-4 barrel engine with dual exhaust and automatic transmission. The black dash and carpet are offset by white door panels and white bucket seats. The black console includes a floor shifter. Other options include clock, N34 Custom Sport Steering Wheel (4 brushed metal spokes), dual sport mirrors with driver's remote control, A/C, and radio.

At the time this Cutlass Supreme went up for sale in 2005 it was in immaculate shape with 99,476 miles on the odometer. The engine compartment was detailed with a 442 sticker added to the air cleaner. This identification was likely an owner addition made when the car was freshened. Although all 1972 Cutlass 442s were registered as Cutlasses (the 442 stepped down to option package once more in 1972) this car lacks the stripes, 442 emblems. Of course the car seems to have been freshly repainted so you never know: this car might have been ordered with 442 package since the 442 option W-29 was now an 'appearance and handling package' available with any engine.

The cowl plate reads:

ST 72 34J67LAN534715 BDY

TR 977 26 PNT

8C A51

72= 1972 Model year

3= Oldsmobile

4J67= Cutlass Supreme convertible

LAN= Lansing, Michigan final assembly plant

534715= Unit number within assembly plant

TR 977= Trim:

26 PNT= Paint: Viking Blue

8C= 3rd week of August, 1971 assembly date

A51= Strato bucket seats

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OCCC CUTLASS SUPREME OVERALL AVERAGE= 10.5 MPG

The original gas log begins on March 18, 1972 at 42.3 miles with a fill of 7 and 2/10th gallons of gas which cost a mere 56.9 cents per gallon. Total cost of the first fill was $4.10. The 1972 Cutlass has a 20 gallon gas tank and as seen below the owner rarely let it drop lower than about 1/4 full.

The gas log is tricky to read and is transcribed as best as possible below. Sometimes a fairly illegible entry can be corrected by comparing per gallon cost with total cost and gallons to see if it all lines up. Figures with a * indicate figures that don't make sense.

Odometer  Gallons   Total cost  Cost per gal MPG (uncorrected)

42.3           7.2        $4.10        $0.56.9       n.a.

197.7         2.5         $1.25       $0.56.9       n.a.

203.5        14.3*      $3.45        $0.56.9      9.6 MPG

304.1         9.3*       $4.25       $0.59.9      10.8 MPG

469.0        11.6*      $10.00      $0.56.9      14.2 MPG

593.4        13.6        $7.44        $0.56.9       9.1 MPG

700.6        10.9        $5.90        $0.52.9       9.8 MPG

840.2        14.3        $8.79       $0.60.9        9.8 MPG

955.2        10.4        $5.49       $0.56.9       11.1 MPG

1,078.5     14.3        $8.05       $0.56.9        8.6 MPG

1,218.1     17?*       $9.00       $0.56.9         8.2 MPG

1,435.1     13.2        $9.35       $0.54.9       16.4 MPG

1,574.3     14.4        $8.35       $0.56.9        9.7 MPG

1,709.7     12.5        $7.30       $0.56.9       10.8 MPG

1,974.9     16.7        $9.30       $0.56.9       15.9 MPG

2,072.5     10.3        $6.25       $0.55.9        9.5 MPG

2,133.2      5.4         $3.20       $0.56.9      11.2 MPG

2,265.1     10.7        $6.00       $0.55.9      12.3 MPG

2,432.8     13.3        $8.35       $0.60.9      12.6 MPG

2,534.6     11.8        $6.30       $0.56.9       8.6 MPG

2,642.1      9.5         $5.50       $0.56.9     11.3 MPG

2,794.8     13.6        $8.30       $0.60.9     11.2 MPG

2,931.1     12.9        $7.05       $0.59.9     10.6 MPG

3,075.2     13.9        $8.15       $0.58.9     10.4 MPG

3,215.7     13.2        $7.90       $0.60.9     10.6 MPG

3,328.5     10.2        $6.00       $0.58.9     11.1 MPG

The average of the MPG calculations is 11.0 MPG. The total miles and gas used starting at 197.7 miles up to 3,328.5 miles is 297.3 gallons to cover 3,130.8 miles which yields 10.5 MPG.

Last Updated ( Monday, 01 May 2017 09:55 )