Home Travel Stories Gas Logs 1975 PLYMOUTH Valiant Custom 225-1 bbl MPG= 12.1 City
1975 PLYMOUTH Valiant Custom 225-1 bbl MPG= 12.1 City PDF Print E-mail
Written by Double Dragon
Monday, 25 August 2014 17:27

1975 PLYMOUTH Valiant Custom 225-1 bbl MPG= 12.1 City


Writing and photography copyright D. S. Brown

Metric= 3.7 L engine- 19.4 L/100km City



The EPA estimated EPA for the Plymouth Valiant at 18 City/ 23 Hwy MPG. This beat the 17 City/ 23 Hwy MPG for a 1975 Dodge Dart with a 225-1 barrel. Correcting to the modern revised EPA standards would knock about 1 MPG off those figures. The Dart is the 'big brother' to the Valiant. It has a 3 inch longer wheelbase and weighs a bit more, hence lower city mileage than baby brother Plymouth.

Thomas McCahill tested a 1975 Dart SE in the Jan, 1975 issue of MECHANIX ILLUSTRATED. The SE is a luxury version of the four door Dart, making it the Dodge equivalent of the Valiant Custom. The curb weight wasn't too bad at 3,372 pounds which included plusher seats and carpets, the V8 318, front disc brakes (required with V8), air conditioning and cruise control. The Dart had E78x14 radials and a low 2.45:1 axle. McCahill said if driven gingerly at 50 MPH it will net 20 MPG.

WORLD CARS 1975 estimated Valiant MPG at 14.3 using the 95 HP 225 engine. WC calculated a top speed of 99 MPH with the manual three speed and 2.76 axle. The top speed would be lower with the automatic installed in the OOCC Valiant. The 1975 WC figures are closer to real life 'as tested' speeds than the very low estimates provided in the WC 1974 edition, so presumably the MPG figures are more accurate as well.

The Oct 1974 issue of POPULAR MECHANICS predicted that a 1975 Plymouth Valiant with 225 and automatic running through a 2.76:1 axle was good for 16.5 MPG overall. The PS figures are likely closer to reality than EPA which operates under ideal conditions. The EPA figure back then was derived from a 31 minute stop start 'city cycle' on dynamometer averaging 20 MPH and a 'highway' run of 12 minutes at an average of 49 MPH.

LEMON AID 1981 EDITION says a 4 door Valiant with 6 cylinder 225 engine, automatic transmission and radio weighs around 3,125 pounds. LA estimated MPG to be 19 MPG using unleaded fuel. LA doesn't specify if the MPG is overall average but does say that the MPG quoted is what the car is optimally capable of under ideal conditions.

LEMON-AID lists earlier Valiant models at 3,000 pounds and even lighter as years roll back. LA says that a 1974 Valiant using unleaded fuel gets 19 MPG, but the 1973 using leaded fuel is credited with 21 MPG. LA states that the 1972 manages 20 MPG, while the 1971 turned in an amazing 22 MPG.


75 valiant custom red front pass side

The OOCC 1975 four door Valiant Custom was bought from the Ensign Pacific Chrysler Plymouth Ltd car dealership in Victoria, BC, Canada. See a story on this dealership filed under BRITISH COLUMBIA/ VICTORIA in the DEALERSHIPS section of this website. The first owner of the Valiant Custom drove it to and from work for several decades. The build date occurs towards the end of the 1975 model year run just as the new 1976 models were being released. The significant digits of the VIN read:

V= Valiant

H= High price class (Custom)

41= 4 Door sedan

C= 225-1 barrel slant 6 engine

5= 1975 model year

B= Hamtramck, Michigan final assembly plant

The fender tag lists some of the options.

75 valiant custom red fender tag

Read from bottom left to right the tag indicates:

E24= 225- 1 Barrel slant 6 engine

D34= Torqueflite Automatic transmission

VH41= Valiant High price class (Custom) 4 door

C5B= 225 105 HP 1975 engine built in Hamtramck, Michigan

The sequence number here has been edited out for owner privacy




721= july 21, 1975 scheduled build date

V1M= White vinyl top

C 0= Built for Canadian market

B43= Front disc brakes rear drums


F18= 65 Amp heavy duty alternator




J52= Inside hood release


L31= Fender mounted turn signal indicators



M21= Drip rail molding

M25= Body sill molding

M26= Wheel lip molding

M38= Deck treatment

N38= Non catalyst exhaust system


R11= Music Master AM Radio

L2= Built on line number 2


The original owner was getting on in age and didn't need a car. He couldn't interest his daughter in the car and reluctantly put it up for sale. The second owner bought the Valiant as a collector car. He stockpiled spare parts and lavished incredible amounts of time and care on the car. The Valiant was always garaged and enjoyed mild warm weather in Victoria, British Columbia.

The OOCC Valiant is all original with the exception of a few items. The windshield wiper blades use modern black plastic attachments and the body color screw on fuel cap has been saved but for daily use it is replaced with a locking cap. The rear window was resealed due to a weather leak. The radiator, tires, exhaust, belts and hoses are stock configuration replacements.

The fender tag indicates the car was built with manual front disc brakes but there is a power booster on this car. As can be seen in the picture below the brake master cylinder intrudes into the proper placement of the air cleaner inlet which suggests the booster/ master combination may not be factory spec.

75 Valiant Custom red brake master cylinder

All maintenance items were attended to immediately and carefully. The engine has never been apart, nor has the transmission. The one barrel 225 slant six engine is famous for being one of the toughest engines out there. The slant design allows the carburetor runners to extend a great long distance without restrictive turns which helps with power and gas mileage. The car has single exhaust and although this is the first year of the catalytic converter which creates backpressure and hurts performance. it seems that this car wasn't built with a catalytic converter. The fender tag tells us it was a cat delete car. The rear axle is the standard 2.76:1 unit.

1975 was a major year for emissions standards and the necessary add-ons sap engine power and MPG. The automatic transmission also saps some efficiency. The car also must contend with more weight than earlier Valiants. Not only does it have emissions equipment, but safety items such as the 5 MPH bumpers add weight. The marketing guys pushed the compacts into a luxury direction resulting in much more content in this car than a typical Valiant which again equals more weight.

The OOCC Valiant was driven in stop and go traffic conditions by a careful driver. The trunk usually carries about 100 pounds of cargo and a full tank of gas most days. The driver weight and occasional passenger weight averages out to about 250 pounds taken overall. The correct size radial tires were kept at 35 PSI. The tires are Nokian WR all season tires. True snow tires have an aggressive tread pattern and soft rubber create more grip but also more inertia for the engine to work against. The 185/65R14 Nokian tires on this car are apparently a new generation of tire which saves fuel via lower rolling resistance despite being acceptable for snow conditions. They are mounted on the original rims with the original hubcaps.

75 valiant custom red front tire

The Consumer Information tells us that a 1975 Valiant with fully operational brakes stops from 60 MPH in 195 feet regardless of whether the car is lightly or heavily loaded. A low speed pass required 10.1 seconds and 450 feet. High speed passing took 20.6 seconds and 1,785 feet. The standard 6.95x 14 inch tires offer a scary 0.1% tire load reserve. That is cutting things right to the bone! Moving up to a D78x 14 creates 6.8% reserve. The E sized tires all have 12.1% reserve. All tires require a 32 PSI inflation. This departure from manufacturer's traditional soft pressures around 24 PSI traces to the new CAFE standards coming into effect. By 1978 the overall production of U.S. cars needed to average 18 MPG. Higher tire inflation reduces rolling resistance and boosts mileage.

75 valiant custom red tire inflation placard

As seen in the tire pressure suggestions in the driver's door jamb soft ride was still put ahead of economy. For softer ride the manufacturer was still suggesting as low as 28 PSI with 4 passengers or less and no luggage. Maximum load (or less) called for 32 PSI.

The owner of the OOCC Valiant alternates Chevron 87 and 89 octane gas between tanks. A modern 10W30 low friction blend of oil is used. Despite all the advantages this Valiant Custom has over the other Valiant Custom in these GAS LOGS (lower total mileage, better condition, better maintenance and higher tires pressures), it posts lower MPG figures.

This log below was recorded during fall and winter ranging from a mild high around 60 degrees F for the first third of the entries down to around the freezing mark for the end of the logs with plenty of rain. The car was filled to the first click off on the pump most times. The Valiant was parked indoors in an unheated garage which provides a smidgen more protection from the weather than being outside all the time. The car was driven in the city and encountered a fair amount of idling at times. The electrical system sees heavy use from with wipers, defrost fan, rear defroster which drains a smidgen of power from the engine. The factory radio was occasionally running for some of the entries.

Odometer  Gallons   Octane  Full Tank?   MPG (uncorrected)

91,388.8     04.9      91    Full tank   n.a.

91,464.6      04.2     91    Full tank   15.4 MPG
91,514.5      03.7     91    Full tank   13.4 MPG
91,546.6      02.6     91    Full tank   12.3 MPG
91,587.0      02.9     91    Full tank   13.9 MPG

91,633.6      04.3     91    Full tank   10.8 MPG

91,692.7      04.2     91    Full tank   14.1 MPG

91,729.8      03.7     91    Full tank   10.0 MPG

91,815.4      06.3     91    Full tank   13.5 MPG

91,849.4      03.2     91    Full tank   10.6 MPG

91,899.6      03.5     91    Full tank   14.3 MPG

91,936.8      03.1     87    Full tank   12.0 MPG

91,983.6      04.3     91    Full tank   10.8 MPG

92,034.7      04.4     87    Full tank   11.6 MPG

92,120.0      08.0     91    Full tank   10.6 MPG

92,224.9      08.2     91    Full tank   12.8 MPG

Adding up the individual averages for the fall/ winter weather and dividing by the number of entries results in 12.2 MPG which does not agree with the overall calculation. It is likely a few of these 'full tank' fills were in reality partial fill ups. Despite this, simply calculating overall totals will reveal closely what true MPG was. Using 71.3 gallons minus the first fill of 4.2 gallons means 67.1 gallons were used to cover 760.3 miles which is 11.3 MPG average in cold city driving.


The figures below are the same type of driving in spring and summer with weather ranging from 50 degrees F to 80 degrees F. Many days were rainy although the last three entries were made during very hot dry weather conditions.

Odometer  Gallons   Octane  Full Tank?   MPG (uncorrected)

92,270.7      03.6     91    Full tank   12.7 MPG

92.381.5      06.4     91    Not full     n. a.

92,441.9      06.6     91    Full tank   13.1 MPG

92,514.7      05.3     91    Full tank   13.7 MPG

92,554.6      03.2     91    Full tank   12.4 MPG

92,645.8      07.7     91    Full tank   11.8 MPG

92,717.1      05.4     91    Full tank   13.2 MPG

Adding up the individual averages for the spring/ summer weather and dividing by the number of entries results in 12.8 MPG.  Using 38.2 gallons minus the first fill of 3.6 gallons means 35 gallons were used to cover 446.4 miles which is 12.7 MPG average which tallies closely with the individual entry averaging.

Adding up a full year of driving for individual entries and dividing by the number of entries produces an overall average of 12.4 MPG. Taking the overall distance of 1,252.5 miles and 107.5 gallons of gas (minus the first fill of 4.2) means it took 103.3 gallons to cover the distance which translates to 12.1 overall city MPG.


The logs below span a full calendar year of city driving at low speeds on side streets.

> 28/AUG/2014 > 28.61L @ 1.579/L = $45.18 ~ 92822.8 MILES

> 08/SEP/2014 > 22.191L @ 1.399/L = 31.05 ~ 92898.8

> 18/SEP/2014 > 20.999L @ 1.399/L = 29.38 ~ 92960.0

> 28/SEP/2014 > 12.320L @ 1.349/L = 16.62 ~ 93007.5

> 05/OCT/2014 > 9.039L @ 1.339/L = 12.10 ~ 93041.7

> 10/OCT/2014 > 14.141L @ 1.309L = 10.51 ~ 93092.9

> 18/OCT/2014 > 12.525L @ 1.239/L = 15.52 ~ 93141.0

> 23/OCT/2014 > 11.820L @ 1.269/L = 15.00 ~ 93177.6

> 01/NOV/2014 > 24.160L @ 1.255/L = 30.32 ~ 93268.3

> 17/NOV/2014 > 33.607L @ 1.269/L = 42.65 ~ 93355.1

> 26/NOV/2014 > 11.453L @ 1.199/L = 13.73 ~ 93397.2

> 12/DEC/2014 > 21.749L @ 1.109/L = 24.12 ~ 93465.8

> 27/DEC/2014 > 29.391L @ 1.219/L = 35.83 ~ 93578.3

>01/JAN/2015 > 17.631l @ 1.155/l = 20.36 ~ 93634.6

> 20/JAN/2015 > 26.658L @ .819/L* = $21.83 ~ 93757.6 (*POINT ROBERTS)

> 03/FEB/2015 > 28.077L @ 1.239/L = 34.79 ~ 93834.1

> 23/FEB/2015 > 33.512L @ 1.339/L = 44.87 ~ 93948.3

> 12/MAR/2015 > 32.411L @ 1.209/L = 39.18 ~ 94066.4

> 20/MAR/2015 > 28.768L @ 1.389/L = 37.18 ~ 94162.4

> 20/APR/2015 > 33.774L @ 1.379/L = 46.57 ~ 94265.7

> 04/MAY/2015 > 30.011L @ 1.349/L = 40.48 ~ 94380.5

> 19/MAY/2015 > 27.605L @ 1.449/L = 40.00 ~ 94494.9

> 30/MAY/2015 > 32.57L @ 1.439/L = 46.87 ~ 94579.6

> 15/JUN/2015 > 30.976L @ 1.539/L = 47.67 ~ 94701.8

> 02/JUL/2015 > 29.693L @ 1.469/L = 43.62 ~ 94803.0

> 16/JUL/2015 > 32.393L @ 1.479/L = 48.21 ~ 94911.1

> 31/JUL/2015 > 25.590L @ 1.459/L = 37.34 ~ 94999.3

> 10/AUG/2015 > 11.329L @ 1.933/L = 15.85 ~ 95044.3

> 23/AUG/2015 > 26.101L @ 1.399/L = 36.52 ~ 95134.0

> 03/SEP/2015 > 19.663L @ 1.339/L = 26.33 ~ 95207.4

> 17/SEP/2015 > 25.999L @ 1.289/L = 33.51 ~ 95288.8



Last Updated ( Friday, 06 March 2020 19:14 )