The best route to trouble-free service from your car is PM -- preventive maintenance. Simply said, remember there's an engine under the hood. David L. Walker of Champion Spark Plug Company asserts:
"An engine may do the job adequately in everyday driving situations, such as to and from the job and the supermarket, but what's going to happen when that same car attempts to pass another car at 55 or 60 miles an hour on a busy two-lane highway?
"That's when performance really counts. In normal driving, the owner may not be aware his engine has a miss. Yet, on the road at sustained highway speeds, the miss becomes evident and also affects fuel economy.
"Aggravating the problem is the fact that this deteioration of performance is so gradual that it's hard to notice."
If your car does not have electronic ignition, a periodic tune-up is essential to keep your car in shape and get the best distance out of a gallon of gas. But no matter what year or model car you have, preventive maintenance is still the best route to trouble-free miles in an automobile.
Cars with electronic ignitions do not require conventional tune-ups in which the points and condenser as well as the spark plugs are cleaned or replaced, timing adjusted, and the engine made shipshape.
"Today, all the manufacturers are using computerized systems in order to get the best balance of performance with emissions control and fuel economy," explains James Kiple, manager of service operations for American Motors Corporation.
"The industry was forced by emission regulations to get into the computer era."
At the same time, technology for automobiles has advanced so far that the service technician is not being asked to be responsible for determining both what the problem is and how to fix it.
Programs designed for removal and replacement of parts are going to obviate his doing both jobs, predicts the AMC executive.
Signals from sensors in the cars will tell the technician the changes which need to be made in fuel-oxygen mixes, for example.
"There'll be more black boxes as we go into the future," asserts Mr. Kiple, speaking of the computer configuration in an automobile.
On-board diagnostic devices are not far from being standard equipment, reports Burton J. Schimpke, manager of the advanced service engineering department for Ford Motor Company. As computers become more widespread, he adds , the whole industry will be moving in that direction.
Mr. Schimpke also points to the rapid decrease in the cost of electronic calculators from perhaps $150 when they were introduced a few years ago to $10 and $15 today.
The same thing is happening to the components of those computers which are designed to eliminate the need for tune-ups and offer on-board diagnosis of any car problems which may be developing. The Ford man says he believes that in the future the cost of repairs won't be as great in proportion to the price of the vehicle as it is today.
Meanwhile, the cost of routine maintenance on a car is dropping sharply. A 1981-model Ford car, according to the manufacturer, for example, has a built-in cost of around $180 for 50,000 miles of operation as compared to $880 in 1973.
To keep a 1971 Dodge Dart working well, the owner's manual advised 115 separate maintenance operations during the first 50,000 miles at an estimated cost of $660.
Chrysler reports the standard maintenance cost for the same number of miles in a 1981 Dodge Aries is around $170.
That figures out to a 74.4 percent reduction i n upkeep.