Revision as of 23:21, 9 January 2013

A stock Datsun 1200, in good condition and state of tune, should get around 38 miles/US gallon in highway travel (16 kilometers/liter). Economy will be less in town, stop-and-go traffic. Note that most 1200 Speedometers are off -- almost always reading more miles that you really traveled -- so base your calculations on a corrected speedometer factor.

1 Overview
2 Other Sunny Models
3 Considerations
4 Engine Tuning Factors
5 Chassis Factors
6 Driver Habits

Overview

The Datsun 1200 got a fuel economy of about 24 city and 38 highway. I used to keep records, and I got about 32 rural/38 highway (after adjustment for speedometer error, see 'top speed' above).

You don't believe it? Here are some actual test results:

MOTORMAN magazine: Range between 24 and 32 miles per gallon. Average on test, 28.9mpg.

Consumer Reports 1971 September Road Test: RANGE OF AS MILEAGE TO BE EXPECTED IN NORMAL USE (mpg) ... 23-41 TANK MILEAGE OBSERVED ON 300-MILE TEST TRIP (mpg) ... 35

28 mpg overall: Road Test - Road & Track (November, 1970)

32.5 on the 1973 Datsun 1200: Motor Trend

35.3 mpg:

We drove the little Datsun from Daytona to St. Augustine and back -- a total of 106 mi. -- on some second-grade roads. At an average speed of 48-plus mpd, the rig from the Land of the Rising Sun got 35.3 mpg, making the round trip on exactly 3 gallons of gas. Mechanix Illustrated

Other Sunny Models

1976 B210 with 4-speed: 41 mpg

B210 and B310 models with FU Engine came with 5-speed and achieved fuel economy that is still unmatched in 2009.

1977 Introducing the B-210 'Plus'

50 miles per gallon
* 63-series 'dogleg' 5-speed and low-RPM A14 engine

1978 B210 - 48/36 TV commercial
http://www.youtube.com/watch?v=jwscXEGp2E4

1978 CANADA "Up to 80km/gal ... Transport Canada approved tests"

http://www.fueleconomy.gov/feg/epadata/78guide.txt
CAL Manual: 40/29 2-dr
CAL Automatic: 30/24 4-dr
FED Manual: 40/28 2-dr no catalytic convertor
FED Manual: 48/36 4-dr catalytic convertor
FED Automatic: 28/24 Coupe catalytic convertor

Nifty Fifty - 1978 USA B210 'Plus' with 5-speed

50 MPG (56 Imperial mpg)
* A14 with 3.700 diff ratio

1979 B310: Winning Numbers From Datsun

47 MPG
* A14 with 3.454 diff ratio
*
* 65 HP A14 (instead of regular 80 HP A14)

Of the 1980 Datsun 210 Coupe, Popular Science magazine said:

This little fuel-squeezer recorded a whopping 67.6 mpg in the 35-mpg section of our steady-state fuel-economy testing -- beating the [USA] EPA-champion Volkswagen Rabbit Diesel.
EPA rating: 43 highway, 31 city, 29 California city
Observed fuel mileage (steady-state mpg)
35 mph: 67.6
45 mph: 50.8
55 mph: 37.3
Specifications: 1.4 liter engine, 65HP @ 5600 RPM, 75 torque @ 3600 RPM, 5-speed manual, 3.70:1 axle ratio, Tire size 175/70SR13, curb weight 2015 pounds, 0-60 mph: 18.4 seconds
February 1980, page 116

1980

Of the 1981 Datsun 210 2-dr sedan 5-speed A14 model, Popular Science magazine said:

EPA rating: 47 highway, 36 city, 30 California city
Observed fuel mileage (steady-state mpg)
35 mph: 58.0
55 mph: 37.9
Specifications: Compression ratio 8.9:1, Tires 155/SR13, Curb weight 1945 pounds, F/R weight distribution 53/47, 0-60 mph 18.0 seconds,
February 1981

Considerations

These factors will greatly decrease your fuel economy:

Weight: Carrying unnecessary weight in the car, e.g. Tools, spare parts, heavier "upgraded" diffs and transmissions. Also having passengers will lower economy. This applies to acceleration (town traffic) and not at all to flat-road highway driving)
Dragging brakes. Jack each wheel and ensure they turn freely by hand. It is not uncommon to have stuck brakes, often due to:
- leaking brake fluid
- leaking axle grease
- seized/unlubricated caliper
- incorrectly adjusted drum brakes
- incorrectly adjusted emergency (parking) brake
Choke not working correctly. With engine fully warm, remove air cleaner and ensure the choke butterfly valve is fully open. Even a little bit off from straight up/down will cause too much fuel to be used

Engine Tuning Factors

Choke freely operating
Choke pulloff working correctly
Choke warming up fully
Distributor Vacuum advance working freely (cars with VA disconnected will use more fuel)
Distributor centrifigal (mechanical) advance freely working
Vacuum leaks
hot Air cleaner intake correctly functioning (warm air is best for fuel economy)
Clean oil
Clean air filter
Fan belt properly adjusted
Emission controls connected and operating
PCV valve not stuck/dirty

Chassis Factors

Brakes not dragging
Correct wheel alignment (most especially toe-in)
Correct tire pressure. Higher pressue is better for fuel economy, up to the limit printed on the tire. However, for proper tire wear, use Datsun's recommendation. Just don't go below it.

Driver Habits

Do not let car warm up for several minutes before driving -- that is 0 miles/gallon when the car is not moving. Start the engine, and drive off moderately after 30 seconds. If your car won't idle this soon, inspect/repair/re-adjust the choke mechanism.
Get into your highest gear as soon as possible, but go as slow as reasonable. This means 4th gear @ 35 mph for a stock 1200. Lower gears use more fuel. Higher speeds use more fuel.
Plan trips. For example, combine two errands into one, instead of making separate trips. Wait for another day to combine errands.
Avoid short trips on cold days, where the choke-on condition uses twice the fuel
Avoid jack-rabbit starts
Avoid last-minute braking
Anticipate stops, approach gradually
Let the car coast faster down hills and go slower up hills if speed laws allow. Otherwise maintain a constant speed.
Install a vacuum gauge in the cockpit and try to keep vacuum as high as possible (by slow, moderate acceleration)
Do not ride the clutch. Your foot should be off the clutch as soon as the car is moving.
Do not ride the brake pedal. Your foot should be off unless stopping/slowing the car
Keep your foot steady on the accelerator pedal
Use regular-grade (inexpensive) gasoline. Your 1200 is designed to run correctly on today's low-octane fuel.

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Fuel economy