Home Travel Stories Gas Logs 1969 MERCURY Cougar 351 MPG= 11.1 Overall
1969 MERCURY Cougar 351 MPG= 11.1 Overall PDF Print E-mail
Written by Double Dragon
Wednesday, 29 December 2010 22:14

1969 MERCURY Cougar 351- MPG= 11.1 Overall average


Writing and photography copyright D. S. Brown, except dealer brochure images copyright Mercury.

Metric= 5.7 L engine- 21.2 L/100km overall average.

The 1969 Mercury Cougar was still a good looking car despite gaining some size for the 1969 model year. After a sales success for the 1967 debut model year, the Cougar sales had dropped in 1968. The decision to go bigger is often sales related and it could be argued that the Cougar size jump for 1969 was inspired by the 1968 sales slump, but this wasn't the reason.

The 1969 Cougar size jump was just a case of following the leader. Cougar was the Mercury version of the Mustang. When the Mustang grew larger, so did the Cougar. Mustang grew in order to accommodate larger engines so it wouldn't get left out of the supercar loop. The Cougar brochures mentioned the size increase and coupled the description 'longer' with 'sportier' as only domestic car advertising would attempt! The big news was the availability of a convertible.


The 1969 Cougar gained some weight due to the size increase, which probably inspired the jump to a larger standard engine this year. The base engine increased from the former 289/ 302 (both were standard at various times) to 351. All of these factors placed the Cougar close in size and engine capacity to the typical 1960s intermediate cars. The wheelbase of 111 inches is one inch shorter than the GM 'A body' intermediates. The Cougar was still billed as a ponycar, but aside from a slightly smaller trunk and marginally shorter length it was basically an intermediate sized car.

69 cougar side front

The OOCC Cougar was ordered March 26, 1969 and built April 15, 1969, six days before the scheduled build date of April 21, 1969. The VIN is decoded below. Significant digits are not shown to protect owner privacy.

9= 1969 model year
F= Dearborn, Michigan final assembly plant
91= Cougar hardtop
H= 351- 2 barrel engine

The door tag provides further detail

65A= Cougar hardtop
C= Dark Ivy Green Metallic Paint Ford # 3197-A
1GA= Light Ivy Gold standard bucket seats
21D= Scheduled build date April 21
A2= Eastern Canada Ordering District
2= Standard 2.75:1 axle ratio
X= FMX Merc-O-Matic transmission

The Cougar came with an optional black vinyl roof, FMX automatic transmission, E78x14 tires, whitewall tires, console, power front disc brakes, power steering, AM radio, remote control left hand racing mirror, and the Sports Special option. This one has the basic Sports Special Value Package A.

9,496 Cougars this year were built with the Sports Special Value Package A. The package included 'bullet' type rocker panels below the doors, E78x14 whitewalls, left hand racing mirror, turbine wheel covers and a mid body stripe. The cost of a Sports Special elevated the price up to $3,111.90.

The big bargain was actually Sports Special Package B. This gave you the appearance items of package A but added in a handling package. You got F70x14 whitewalls on 6 inch rims, heavier front stabilizer bar with heavy duty shocks and springs for only $3,139.10. The vinyl roof on the OOCC Cougar probably cost more than the minimal cost of jumping to Sports Special B.

The OOCC Cougar was bought new on June 30, 1969 by a mechanic who parked the car at the end of the 1970s with 80,000 miles because of rust. The mechanic asserted that "not one bolt on the engine was ever touched". After sitting in the first owner's driveway out in the open for a few years the Cougar was rescued. The collector who bought kept it in dry storage for 4 years until he could get to the car. He replaced the floors and all rusty metal before repainting in the original color. He installed aluminum 'go faster' replacement front fenders. The interior was untouched.  Mechanical repairs included a new universal joint, heater core, an idler arm, new wheel cylinders in rear and new calipers and brake rotors up front. The collector added new Superlift Load Leveler air shocks.


The bottom of the back cover has the date of printing of the original owner's manual: issued Jan, 1969. The Cougar was ordered March 26, 1969 and built in Dearborn, Michigan Tuesday April 15, 1969, six days ahead of the scheduled build date. It was released from the factory April 16, 1969.


The Cougar collector who rescued this car was a 'project person': someone who derives satisfaction from restorations then looks to the next car. He drove it less than a hundred miles before selling. He had factory 427 Cougars in a barn and other Cougars sprinkled throughout his property.

The collector kept the original code C Dark Ivy Green Metallic color when repainting and retained the original optional black vinyl roof. The Light Ivy Gold interior was left alone, being in good enough shape to just need a good cleaning. The original AM radio was replaced with a typical 1970s era cassette stereo player. A block heater appears to be an aftermarket addition. The white stripe E78x14 tires were gone, replaced with an oversized late 1970s set of Wide Oval white raised letter bias ply tires.

The detailed gas logs that survive document MPG with the original Autolite carburetor and air cleaner assembly, stock heads, manifolds and single exhaust. The tires, battery, fuel filter, plugs and wires were new but everything else was factory original. At some point in the history of the car, a manual choke was installed with an under dash control which really didn't accomplish much. The Cougar was impossible to start in cold weather but ran well once it was going.

The Cougar ran bias ply Wide Oval tires for the first 1,000 miles of the detailed logs. On bias ply tires, which are not known for good mileage the car returned 16.6 MPG while being driven very hard and quick on a short work commute of 4.2 miles one way. The car was usually driven to a girlfriends' place 16 miles away on two lane blacktops at about 70- 80 MPH which was about the maximum the skittish fat bias ply tires could handle. Wide bias ply tires rip the car sideways with a sudden jerk as they follow grooves and uneven pavement resulting in unsettled high speed driving.

The Cougar usually carried only driver weight. Adding occasional passenger amounts and taking into account weight shaved off by perennially low gas tank levels leaves the car about 100 pounds above curb weight on average. The Cougar curb weight was 3,358 pounds. The 120 pounds of curb weight accounted for by the full gas tank of 20 gallons has to be removed because the car was frequently driven at or below a quarter tank.

The Cougar proved to be less resilient than a Mopar of the same vintage. GM cars also held together a bit better, but weren't as tough as the Chryslers. The Cougar sway bar, transmission mounts, and engine mounts broke during typical high speed two lane blacktop maneuvers that Chrysler cars endured without problems. The Cougar engine mount failure resulted in the oil filter getting crushed when the engine dropped causing a drastic oil pressure drop at high speed. Not good. The Cougar received new engine and transmission mounts and transmission lines. The sway bar was changed to a heavier unit as were the shocks.

The engine was trouble free and soldiered on anvil tough while the water pump blew up from the steady diet of crazy RPMs and the power steering belt shredded at sonic speeds. The only issue with the engine was replacement of one frost plug. This probably traces back to the period where owner number one left the car sitting for several years. Antifreeze becomes acidic over time. The front disc brakes were excellent and absorbed abuse equal to astronaut deceleration g force training sleds without a whimper.

Aside from the engine and brakes, the Cougar proved to be somewhat fragile in general. The passenger window is glued to the lift. The bond weakened and the glass vanished into the inside of the door one day in minus 40 weather pelting snow into the passenger seat. Other Cougar model years used a riveted arrangement rather than bonding the windows in place. The expected failure of the Ford sequential turn signal system also occurred. The windshield washer failed in sleet ice conditions and the neutral safety switch gave up the ghost late one night.

At 83,683 miles the Wide Oval bias ply tires were switched to 205R70x14 radials which are the modern equivalent size of the original factory tires. The new radials were mounted on the original rims with the original Sports Special 'turbine' hubcaps to preserve factory correct external appearance. Once the radials were in place the Cougar was frequently driven at a sustained 120 MPH on back country highways for trips of 5 to 10 miles. Amazingly, the 351 still had more speed left in it due to the very low 2.75:1 rear axle ratio. The Cougar shifted through an FMX Merc-O-Matic automatic transmission.

Around the time of the tire change a job change subjected the Cougar to a 5 mile work commute with about 3 miles of sustained 100 to 120 MPH blasts. Several thousand miles later business relocation extended the commute to 6 miles each way devoid of highway straight-aways. The commute was choked with endless burning rubber wide open throttle stop light to stop light driving. Before the car completely cooled off it was used again to travel 2.9 miles on two lane blacktops into the country for lunch thus ensuring that decent operating temperatures were achieved on each trip. Coming home, a detour to pick up a girlfriend, cruising around, regular physiotherapy sessions and ferrying the girlfriend to nightclubs, to the driver's home and then back to her house and back home again after that added at least another 40 to 50 miles a day. The Cougar was used around the clock.

There are no complete fill ups in the fragmentary log below, but taking one empty to empty notation will give a general indication of MPG. The 4,910 miles between "Empty" readings on the gas gauge at 82,850 miles and 87,760 miles used 297.3 Gallons from Empty to Empty. Subtracting the last fill of 1.6 gallons means 295.7 gallons were used to keep the tank at the same level. This works out to 16.6 MPG, incredible mileage for someone driving full throttle acceleration/ high speed highway runs.

The log below has columns for the odometer reading, gallons of gas added, octane of gas if noted, and notes about tank levels if noted. When it says Leaded/ Unleaded this means that a mixture of 50% leaded gas was combined with 50% 94 octane unleaded.

Odometer Gallons Octane Fill?  MPG (uncorrected)
82,650                          X
82,770       5.5               X
82,850      11.0              E to 3/4
82,990       8.2               X
83,107       3.8              X
82,236       5.5              X
83,325       3.3              X
83,385       1.3              E to 1/8
83,402       3.3              E to 1/4
83,444       6.0              X
82,566       2.7              Ran out-E
83,598       5.5              X
83,683       3.3              X
83,707       5.5              X
83,000       0.0              X
83,770       3.8              X
83,820       2.7              X
83,870       3.3              X
83,904       2.7              X
83,948       3.3              X
83,981      10.1             X
84,198       2.7              X
84,247       5.5              X
84,280       2.7              X
84,315       5.5              Empty
84,373       5.5              X
84,550       2.7              X
84,589       2.7              X
84,642       3.8              X
84,682       2.2              X
84,622       2.2              X
84,764       2.7              Empty
84,795       2.2              Empty
84,850       5.5              X
84,895       5.5              X
84,978       8.2              E to 1/2
85,101       2.0              X
85,000      11.0             X
85,238       1.2              X
85,257       8.8              X
85,658       5.5              X
85,766       2.7              X
85,770       1.6              X
85,785       3.8              X
85,828       5.5              X
85,890       3.3              X
85,960       2.7              X
86,004       6.6              X
86,100       5.5              X
86,500       0.0              X
86,600       5.5              X
86,707       5.5              X
86,765       4.4              Empty
86,820       2.7              X
86,853       5.5              X
86,900       5.1              X
87,043       3.8              X
87,004       2.7              X
87,100       2.7              X
87,140       2.7              X
87,173       2.7              X
87,210       6.6              X
87,338      13.7    94 oct Leaded
87,270       5.5     Leaded/ 94 Unleaded
87,505      11.0    Leaded/ 94 Unleaded
87,655      10.5    Leaded/ 94 Unleaded
87,760       1.6              Empty
87,770       6.1              X
87,820       0.8              X
87,834       5.5              X
87,900       3.3              X
87,986       1.6              X
88,009       0.0               X
88,080       4.4              X

The surviving summary log below was created from lost original logs. It's fairly accurate since the first two MPG entries in the summary cover the miles from the detailed logs and both agree on MPG.

The MPG numbers from the summary page below were recorded after a switch of carburetors. The original plan was just to solve the Cougar cold weather starting issues. At 83,707 miles a speed shop replaced the stock air cleaner, Autolite carburetor and manual choke with a gigantic chrome low restriction open element air filter on top of a freshly built Holley performance carburetor sporting huge jets plunked atop an Edelbrock intake. The Cougar started immediately in extreme weather. It was also so much faster it was shocking.

At 87,200 miles a second visit to the speed shop for a tune-up resulted in the typical "more is better' process. The Cougar came in for dwell, timing, plugs, wires and distributor which it got. The bewitching array of shiny speed equipment displayed on the waiting room walls led to the Cougar receiving mild headwork, cam and headers feeding duals with glass packs. The Cougar now roared like a muscle car. In stock form the Windsor 351 2 barrel single exhaust was good for 250 HP. Switching to a four barrel and higher compression results in 290 HP. A cam, headers and headwork probably knock this up to somewhere in the 320 to 340 HP range. Purists will be relieved to know that all factory parts were saved and reinstalled on the car a few years later prior to being sold.

69 cougar side

A summary log below provides a long term history of gas use. This log shows a healthy 16 MPG using the frugal Autolite carburetor with stock timing and heads. The figures plunge to 11 MPG and even lower after the performance modifications were made. The Cougar was driven harder and faster once modifications were done, so it's hard to know for sure if it was the chicken or the egg.

The Edelbrock intake, headers and dual exhaust were sold and the original cast iron manifolds were reinstalled for the last few hundred miles which mysteriously show an increase in MPG despite the restrictive qualities of factory manifolds. The explanation is likely due to the original single exhaust system being too rotted to hook up properly aft of the crossover pipe. The effect is similar to having an 'uncorked exhaust' which could be heard from several blocks away. Taking the overall summary, we have 1,246.3 gallons of gas to drive 13,854 miles which works out to about 11.1 MPG overall.

Odometer Gallons per/Month   MPG (uncorrected)
83,700        65.1      16.2 MPG
85,194        87.9      16.9 MPG
86,194        69.2      14.4 MPG
87,364        99.0      11.8 MPG
88,125        66.7      11.4 MPG
89,325      108.4     11.0 MPG
90,634      117.5     11.1 MPG
90,927        24.7      11.8 MPG
91,191        41.2       6.4 MPG
91,954        70.3      10.8 MPG
92,693        82.4       8.9 MPG
93,265        68.6       8.3 MPG
94,054        60.4      13.0 MPG
95,104        82.4     12.7 MPG
95,854        68.5     10.9 MPG
96,934        96.9     11.1 MPG
97,554        37.1     16.7 MPG












Dearborn noon

SU 25 AR- MO 12 AR- ME 3 TA- VE 14 AR- MA 15 SG- JU 28 VI- SA 28 AR- UR 0 LI- NE 28 SC- PL 22 VI- NN 0 AR

SU inc JU/ SU inc NE/ SU inc PL/ ME bq JU/ ME incj UR/ VE tr MA/ MA ssq SA/ JU inc SA/ JU sx NE/ SA incj NE/ SA bq PL/

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