Japan puts diesels in pickups to boost the workhorse mileage

The first thing a friend said to me about the new Datsun King Cab diesel truck was: "It's so quiet." Indeed, the friend bought a Volkswagen diesel-engine sedan a few months ago and says the Japanese pickup, by contrast, makes less noise. Whether it does or not, that was his impression, at least.

At cruising speed on the highway, and with the transmission in fifth gear, the Datsun diesel truck purrs gently, so much so that you can almost forget the engine is there.

Also, the King Cab, restyled along with Nissan's other pickups a year and a half ago, is cheap to run. On the highway under steady-state driving, the diesel-engine pickup will easily top 40 miles per gallon -- and even approach 45 . In city-type driving, the figures expectably fall.

The gasoline-engine version of the King Cab costs hundreds of dollars less and gives far faster response to a push on the accelerator. But over the long pull, the slower-responding diesel will save money because of the generally lower cost of diesel fuel and the better mileage to boot.

The diesel engine starts readily although it may take 20 seconds, and longer in cold weather, to get under way. If you don't want to wait for the engine to start, then the diesel is not for you.

A diesel-truck buyer has to remember that a truck is a workhorse and not a car. Thus, while the appointments are good as small trucks go, a truck is still a truck. In other words, the King Cab is poised to do a job even while ready to take you to the beach or the hills. Then the next morning it can go back to work along with the driver.

Leg room is phenomenal -- and there is plenty of space behind the seat to stow whatever you want to stow, so long as it will fit through the door.

Toyota also has put a diesel engine into its long bed pickup, the first diesel it has sold in the US although it has been marketing oil-burning engines in other parts of the world for the last 20 years.

Both the Datsun and Toyota diesel engines are about the same size and horsepower and give the same performance.

Isuzu also is moving into the US with its own line of diesel-engine vehicles, including the I-pup pickup. General Motors has made an Isuzu diesel engine an option in the Chevrolet Chevette although the number of engines available is expected to remain low for the year.

Diesel-engine vehicles, both light trucks and passenger cars, are growing fast in the US, with some of them turbocharged to provide better performance on the road. While pokey performance, smoke, and smell are endemic to the engine, the engineers continue to improve the concept. The Datsun King Cab diesel, for example, emits almost no smoke. and I have yet to get a whiff of the fuel inside the cab.

Roger Smith, chairman of General Motors, expects a bright diesel future for GM, predicting that by the mid-1980s the oil- burning engines could reach 20 and even 25 percent of all GM cars.

The 2-wheel-drive Datsun King Cab pickup moves from 0 to 30 miles per hour in about 5 seconds, compared with less than 4 seconds for the low-emission gasoline engine; and 0 to 60 m.p.h. in 19.2 seconds vs. 12.8 seconds for the conventional power plant.

Base price of the King Cab diesel is $7,679. Air conditioning costs $580. An automatic transmission is not yet available on the diesel.

But like more diesel engines in the future, it's coming.