Chrysler 300 Letter Series

Chrysler 300 Letter Series: which version to choose (1955 vs 1957)

If the question is which Chrysler 300 Letter Series to pick, the data set only has two production years and five named versions. 1 generation (1955) is a Coupe Hardtop with one 5.4 AT at 305 hp and 1900 kg. 3 generation (1957) is a Cabrio with four 6.4 AT rows that share the same name: two at 380 hp and two at 396 hp, each power split again by kerb weight 2000 kg or 2070 kg.

If the question is which Chrysler 300 Letter Series to pick, the data set only has two production years and five named versions. 1 generation (1955) is a Coupe Hardtop with one 5.4 AT at 305 hp and 1900 kg. 3 generation (1957) is a Cabrio with four 6.4 AT rows that share the same name: two at 380 hp and two at 396 hp, each power split again by kerb weight 2000 kg or 2070 kg. There is no 0–100, top speed, or mpg figure on any row, so the ranking below is power, torque, litres, gears, tank, and kilograms only.

Queries such as “1962 Chrysler 300 Letter Series”, “1965 Chrysler 300 Letter Series”, “Chrysler 300 non letter series”, and “is the Chrysler 300 coming back” sit outside this catalogue: the measured years here are 1955 and 1957 only, and no non-letter or later-year version is in the data.

Chrysler 300 Letter Series generations compared

1 generation (1955-01-01 to 1955-12-31) is the lighter, smaller-engined choice: Coupe Hardtop, 1 version. The 5.4 AT is a 5425 cm³ Gasoline 8-cylinder V-shaped unit, 2 valves per cylinder, boost No, Front, longitudinal, Carburetor, compression 8.5, bore and stroke 95.8 × 92.1, Automatic with 2 gears, RWD. Peak is 305 hp (224 kW) at 5200 rpm and 468 Nm at 3200 rpm. Kerb weight 1900 kg, tank 76 l. Fuel grade, 0–100, top speed, city/highway/combined consumption, CO2, eco class, gross weight, ground clearance, and wheel size are not measured.

3 generation (1957-01-01 to 1957-12-31) is the open-body, larger-engine choice: Cabrio, 4 versions, all labelled 6.4 AT. Every 1957 engine is 6435 cm³ Gasoline, 8 cylinders, V-shaped, 2 valves per cylinder, boost No, Front, longitudinal, Carburetor, compression 9.25, bore and stroke 101.6 × 99.2, fuel 76, Automatic with 3 gears, RWD, tank 87 l, drum brakes front and rear, Independent, torsion front, Dependent, leaf spring rear. The four rows differ only in output and kerb weight:

• 6.4 AT 380 hp (280 kW) at 5200 rpm, 570 Nm at 4000 rpm, 2070 kg
• 6.4 AT 396 hp (291 kW) at 5400 rpm, 570 Nm at 4000 rpm, 2070 kg
• 6.4 AT 380 hp (280 kW) at 5200 rpm, 570 Nm at 4000 rpm, 2000 kg
• 6.4 AT 396 hp (291 kW) at 5400 rpm, 570 Nm at 4000 rpm, 2000 kg

What 1957 changed versus 1955, in arithmetic on these numbers: displacement +1010 cm³ (6435 − 5425), compression +0.75 (9.25 − 8.5), gears +1 (3 versus 2), tank +11 l (87 − 76), peak torque +102 Nm (570 − 468), and kerb +100 kg or +170 kg versus the 1900 kg Coupe Hardtop, depending on which Cabrio row you take. Body type also changes: Coupe Hardtop in 1955, Cabrio in 1957. Peak torque arrives later on the 6.4 (4000 rpm versus 3200 rpm on the 5.4).

Engine and specs: every Chrysler 300 Letter Series version

Power per litre (hp ÷ displacement in litres): 5.4 AT 305 / 5.425 ≈ 56.2 hp/l; 6.4 AT 380 hp 380 / 6.435 ≈ 59.1 hp/l; 6.4 AT 396 hp 396 / 6.435 ≈ 61.5 hp/l. The 1957 396 hp row is about 5.3 hp/l above the 1955 5.4 AT. The step from 380 to 396 hp on the same 6435 cm³ is +16 hp and +11 kW, with peak power 200 rpm higher (5400 versus 5200). Torque does not change among the four 6.4 AT rows: all 570 Nm.

Performance, mpg, and what is not measured

0–100, maximum speed, city consumption, highway consumption, mixed consumption, CO2, and eco class are not measured on the 5.4 AT and on every 6.4 AT. There is no mpg ranking and no acceleration ranking in this data. Fuel grade is not measured on the 1955 5.4 AT; every 1957 6.4 AT lists fuel 76.

What can still be ranked without inventing a sprint time is specific output and mass per horsepower (next section). A 16 hp gap at identical 570 Nm and identical 6435 cm³ means the 396 hp 6.4 AT is the higher-revving tune of the same displacement, not a larger engine. A 75 hp gap (380 − 305) and a 91 hp gap (396 − 305) are the generation step, not a trim option inside 1955.

Dimensions, weight, tank: kg per horsepower

Gross weight, ground clearance, and wheel size are not measured on any version.

Kerb weight and tank:

• 5.4 AT: 1900 kg, 76 l
• 6.4 AT 380 hp and 6.4 AT 396 hp at 2000 kg: 2000 kg, 87 l
• 6.4 AT 380 hp and 6.4 AT 396 hp at 2070 kg: 2070 kg, 87 l

Mass per horsepower (kerb kg ÷ hp):

• 5.4 AT 305 hp: 1900 / 305 ≈ 6.23 kg/hp
• 6.4 AT 380 hp, 2070 kg: 2070 / 380 ≈ 5.45 kg/hp
• 6.4 AT 380 hp, 2000 kg: 2000 / 380 ≈ 5.26 kg/hp
• 6.4 AT 396 hp, 2070 kg: 2070 / 396 ≈ 5.23 kg/hp
• 6.4 AT 396 hp, 2000 kg: 2000 / 396 ≈ 5.05 kg/hp

The light 396 hp 6.4 AT is 1.18 kg/hp lighter than the 5.4 AT (6.23 − 5.05). Inside 1957, dropping 70 kg at 380 hp improves the ratio by about 0.19 kg/hp (5.45 − 5.26); dropping 70 kg at 396 hp improves it by about 0.18 kg/hp (5.23 − 5.05). Taking 396 hp instead of 380 hp at the same 2000 kg is 16 extra hp on the same kerb, about 0.21 kg/hp better (5.26 − 5.05). Taking 396 hp at 2070 kg versus 380 hp at 2000 kg is almost a wash: 5.23 versus 5.26 kg/hp — the extra 16 hp roughly offsets the extra 70 kg.

Tank per kg: 76 / 1900 ≈ 0.040 l/kg on the 5.4 AT; 87 / 2000 = 0.0435 l/kg and 87 / 2070 ≈ 0.042 l/kg on the 6.4 AT rows. The Cabrio carries 11 more litres on a car that is 100 or 170 kg heavier.

Chassis labels that do not change the ranking: all five versions are RWD with Drum front and Drum rear brakes and Dependent, leaf spring rear suspension. Front suspension is Independent, spring on the 1955 5.4 AT and Independent, torsion on every 1957 6.4 AT.

Which Chrysler 300 Letter Series version to choose

Choose the 1955 Coupe Hardtop 5.4 AT if the body is the point and you want the lowest kerb in this set (1900 kg) plus the earliest torque peak (468 Nm at 3200 rpm). You give up 75 or 91 hp, 102 Nm, 1010 cm³, one gearbox ratio (2 versus 3), 11 litres of tank, and the Cabrio body. Specific output is the lowest of the five (≈56.2 hp/l) and mass per horsepower is the highest (≈6.23 kg/hp). Fuel grade is not measured on this row.

Choose a 1957 Cabrio 6.4 AT 380 hp if you want the 6435 cm³ engine, 3-speed Automatic, 87 l tank, and 570 Nm, but not the 396 hp tune. Distinguish the two 380 hp rows by weight: 6.4 AT 380 hp at 2000 kg is 70 kg lighter than 6.4 AT 380 hp at 2070 kg at the same 380 hp, 280 kW, 5200 rpm, and 570 Nm. That 70 kg is the entire difference between those two catalogue lines.

Choose a 1957 Cabrio 6.4 AT 396 hp if the ranking is power and kg/hp. Both 396 hp rows make 396 hp (291 kW) at 5400 rpm and the same 570 Nm as the 380 hp rows. 6.4 AT 396 hp at 2000 kg is the best mass-to-power figure in the data (≈5.05 kg/hp) and the highest specific output (≈61.5 hp/l). 6.4 AT 396 hp at 2070 kg is 70 kg heavier at the same 396 hp; its ≈5.23 kg/hp is almost identical to the light 380 hp row’s ≈5.26 kg/hp, so the extra 16 hp is spent carrying the extra 70 kg.

Do not treat “6.4 AT” as one car. The name is shared four times. Separate them as: 380 hp / 2070 kg, 396 hp / 2070 kg, 380 hp / 2000 kg, 396 hp / 2000 kg. Torque, displacement, fuel 76, 8-cylinder V-shaped layout, boost No, Automatic 3, and RWD are the same on all four.

Generation versus version. Moving from 1 generation to 3 generation is the large step: +1010 cm³, +0.75 compression, +1 gear, +11 l tank, +102 Nm, Coupe Hardtop to Cabrio, Independent, spring to Independent, torsion, and +100 or +170 kg. Moving among the four 1957 6.4 AT rows is the small step: only 16 hp and/or 70 kg. There is no measured 0–100 or mpg to say the 16 hp is “felt,” and there is no price field, so “what the extra money buys” cannot be answered in currency — only in +16 hp, +0 rpm of torque, and −70 kg if you take the light row.

Reliability / problems. No reliability, recall, or problem counts are in the data. What is documented is mechanical commonality: Gasoline, Carburetor, 8 cylinders, V-shaped, 2 valves per cylinder, boost No, Front, longitudinal, RWD, Drum/Drum on every version. Differences that could matter in use are 2 versus 3 Automatic gears, Independent, spring versus Independent, torsion at the front, 76 l versus 87 l tank, fuel not measured versus fuel 76, and the four-way 380/396 hp and 2000/2070 kg split on the Cabrio.

If the search was “Chrysler 300 Letter Series 1955,” the only match here is the 5.4 AT Coupe Hardtop. If the search was the Letter Series as a performance catalogue, the 1957 6.4 AT 396 hp at 2000 kg is the strongest kg/hp and hp/l row in this file; the 1957 6.4 AT 380 hp at 2070 kg is the heaviest for its power.