Article

Test Drive: Isuzu NPRs Offer High Maneuverability

A 4-cylinder diesel promises to sip fuel while a gutsy gasoline V-8 saves upfront money and really goes.

March 2016, TruckingInfo.com - Test Drives

by Tom Berg, Senior Editor - Also by this author

SHARING TOOLS        | Print Subscribe
The NPR Gas (left) and NPR diesel share cabs and chassis components. Wheel cuts were tight and turning circles short for both models. The trucks are bigger than they look; the 81-inch-wide steel cabs are solid and roomy enough for three people each. Photos: Tom Berg
The NPR Gas (left) and NPR diesel share cabs and chassis components. Wheel cuts were tight and turning circles short for both models. The trucks are bigger than they look; the 81-inch-wide steel cabs are solid and roomy enough for three people each. Photos: Tom Berg

You see them mostly in cities – compact cab-over-engine trucks that scurry around purposefully, darting into tight streets and alleys to leave goods with merchants or taking tradesmen to deliver services. In the suburbs they turn easily into driveways, whose owners don’t fear for the integrity of their pavement or lawns because those “little” trucks couldn’t hurt anything.

Although conventional-cab trucks sell best by far in North America, 15% to 20% of buyers choose cabovers for their various advantages, including more frame devoted to hauling space, lighter weight, and shorter overall length.

While conventionals have seen a move to tighter wheel cut and improved maneuverability, nothing turns corners like a cabover. Want to make a U-turn in the space of two and a half or three lanes? No problem with the two Isuzu trucks you see here.

Isuzu Commercial Truck of America and its dealers sell two-thirds to three-quarters of all low cabovers (or low cab-forwards, as they’re also called), by virtue of the Japanese brand’s long presence here and a large dealer network. The builder recently revived its association with a reinvigorated General Motors, so later this year Chevrolet truck outlets will resume handling private-branded Isuzu-built cabovers, which was suspended in 2009 during GM’s bankruptcy. Isuzu offers the 2-door standard cab, as we had this day, as well as 4-door crew cabs.

The drive

We drove three Isuzu models around Orange and Riverside Counties in southern California last month, starting at Isuzu’s headquarters in Anaheim and heading as far as Beaumont on Interstate 10, then returning to I-215 and south to Perris. There we paused for photography and I used the Orange Empire Railway Museum’s parking lot to try circles and backups.

It’s been several years since I handled an Isuzu, and it was good to get reacquainted. I drove a 13,000-pound-GVW NPR diesel and a 14,500-pound NPR Gas, and we also had a16,000-pound NPR-XD diesel along. There were no loads in the van bodies so our impressions were limited, except that ride quality was very good – no stiffness or jouncing, thanks to the compliant leaf springs front and rear.

Door opens 90 degrees, step is decently sized and A-pillar’s grab handle helps driver climb in. Entry and exit become graceful exercises after a little practice. 
Door opens 90 degrees, step is decently sized and A-pillar’s grab handle helps driver climb in. Entry and exit become graceful exercises after a little practice.

I first hopped in the 13K NPR diesel because it’s the latest model, and is an example of the builder designing specialty sub-models within the N series. With its 170-inch wheelbase, it can handle bodies up to 20 feet long with an overall length of under 30 feet. The diesel is the same inline 4 that’s used in the 12,000-pound NPR Eco-Max model. It makes up to 150 hp and 282 lb-ft. It runs through a 6-speed Aisin automatic transmission that keeps revs within reasonable bounds – about 2,400 rpm at 70 mph.

It’s the torque that mostly motivates the truck at lower speeds, but horses are required at highway speeds, and the Aisin often kicked out of its overdrive 6th and 5th gears to raise revs while climbing grades. The small diesel makes a low-pitched burble that rises a few notes as revs climb. The sound is enough to say “I’m working” but it doesn’t shout about it. An exhaust brake is controlled by a switch on the dash and a stalk on the right side of the steering column.

The small 3-liter diesel nestles between the frame rails and is in plain view when cab’s tilted. The blue-capped tank carries diesel exhaust fluid for the aftertreatment system on the right side of the truck.
The small 3-liter diesel nestles between the frame rails and is in plain view when cab’s tilted. The blue-capped tank carries diesel exhaust fluid for the aftertreatment system on the right side of the truck.

Engine options

“In this country we’re horsepower crazy,” said Isuzu product manager Mike Kelly in explaining Isuzu diesels’ modest sizes, output numbers and performance. The small diesel’s horsepower is half what buyers get with many domestic conventionals. But Isuzu’s power-to-weight ratios are more in line with “real” rigs. The NPR’s acceleration was more than adequate for hauling low-density loads, and it keeps up with traffic while conserving fuel. We didn’t keep track of fuel economy, but it’ll probably be at least half again more than with a 300-horse V-8 diesel. (Heavier Isuzu models, including a 14,500-pound NPR-HD, use a stronger 215-hp, 452-lb-ft, 5.2-liter diesel.)

But for real guts, there’s the NPR Gas. The engine’s a GM Vortec 6000, a 6-liter gasoline V-8 rated at 297 hp and 372 lb-ft, running through a 6-speed Hydra-matic. This thing really goes. Taking off from a dead stop, I had to ease into the gas pedal because the truck would otherwise slingshot away. Once moving it was exhilaratingly lively, on the level or while climbing hills, and rather quiet, too. With eight pistons the engine sounded busier than the four-cylinder diesel, cruising about the same rpms at 70 mph, but still was rather quiet.

However, the point of an NPR Gas is not performance, but cash conservation up front. It costs about $8,000 less to purchase than the diesel, Kelly estimated, and with that dough you can buy a lot of cheap gasoline. It makes even more sense if the truck sits around a lot while its driver is working elsewhere (if he shuts off the engine, of course; the diesel comes with programmable idle shutdown, by the way). The NPR Gas’s engine can be had with hardened valves and valve seats so it can burn propane or natural gas, and Kelly said about 30% of Isuzu dealers order the engine that way. Approved conversion kits are readily available.

One of the best things about a cabover is that the cab tilts up and forward, yielding an unobstructed view of the engine, radiator and part of the transmission. Mechanics have to love this. The cab must be unlocked and raised by hand; it’s not light, but well balanced, and after a few tries it becomes fairly easy. A folding arm behind the hinges locks the cab in the up position so you can lean in and check the single drive belt and coolant hoses. Dip sticks for engine oil and transmission fluid are on the left side of the powertrain. When you’re done, you reach forward and unlock the support arm and ease the cab down until it pops into place; then pull down the latch handle and you’re good to go.

The climb into the cab is a little more awkward than on a conventional because the single step is forward of the seat. You pull open the door (it swings out 90 degrees, allowing lots of entry and exit room); put your left foot on the step, which is about 16 inches off the ground, and your left hand on the A-pillar’s handle and right hand on the steering wheel; pull your body up and swing your right foot inside and onto the floor, then move into the cab and sit down. Don’t buckle up ‘til you reach out and close the door. It takes a little practice, as does climbing out. 

It’s worth it for the clear view forward and to the sides, aided by remotely adjustable mirrors (flat and convex glass in both are remotely adjustable). And when underway, there’s the joy of spinning the wheel and feeling the truck turn so sharply.

In the cab

The driver’s seat is supportive, and shifter and parking brake are conveniently close by. Gauges are few but adequate, and three-knob HVAC controls are easy to use. Visibility and maneuverability are excellent.
The driver’s seat is supportive, and shifter and parking brake are conveniently close by. Gauges are few but adequate, and three-knob HVAC controls are easy to use. Visibility and maneuverability are excellent.

The driver’s seat is firm but bucket-like in its support, and the diesel NPR had a mechanical suspension seat that can be adjusted with a dial-like wheel on the forward edge of the seat frame. I left it alone but pulled the seat forward a few inches to reach the two pedals. The steering column tilts and telescopes to accommodate drivers of various proportions. I was very impressed with the feel of the hydraulic brakes – just the proper amount of pedal travel with swift, sure and utterly straight stopping power. A paddle-type shift selector is directly to the right and easy to manipulate. Both the Aisen and the Hydra-matic have a Park position.  The parking brake is set with a lever, also to the right.

The instrument panel has only a speedometer, tachometer and a couple of smaller gauges for engine coolant temperature and fuel level. In this day’s bright sunlight (this was sunny California, after all), the instruments were a little hard to see, and I’d have preferred larger sizes as well as more gauges for additional information. Most switches were flat rockers or twist knobs on stalks. Against that sun the pull-down visors were large, effective and easy to manipulate. The diesel truck had a Bluetooth-enabled radio, which can link to a smartphone and other devices, but I didn’t get the opportunity to try it out. 

The cab is tall so there’s good headroom, and two shelves above the windshield to store paperwork, folders and maybe a laptop. Steering on the diesel truck was a little twitchy, but it was steady on the gasoline version. The gas truck had a cab-mounted shield that guided air flow over the van’s roof, and that probably helped settle down the chassis at higher speeds.

For the last leg of the trip I again grabbed the NPR Gas because I really enjoyed its power. The sun had set and darkness had set in by the time we returned to Isuzu’s headquarters, so I got a look at the decent illumination of the gauges and effectiveness of the reflector-beam headlamps.  I backed the truck into a stall on the parking lot and was a little sorry to leave it. 

Specifications

Truck

Isuzu NPR low cabover, BBC 109 in., GVWR 13,000 lbs.

Engine

Isuzu 4JJI-TC 4-cyl. diesel, 3 liters (183 cu. in.), 150 hp @ 2,800 rpm, 282 lb-ft @ 1,600-2,800 rpm, turbocharged and aftercooled, w/ exhaust brake and SCR exhaust aftertreatment

Transmission

Aisin A460 6-speed automatic, 5th and 6th overdrive

Front axle

6,830-lb. Isuzu, on 8,440-lb. tapered multi-leafs

Rear axle

11,020-lb. Isuzu, on 12,090-lb. tapered multi-leafs

Differential ratio

 5.125 to 1

Wheelbase

170 in.

Tires & wheels

215/85R16E on steel discs

Brakes

Vacuum-boosted hydraulic, discs front, drums rear

Fuel tank

 25-gal. steel

Body

20-ft. Morgan aluminum sheet-and-post van

(NPR Gas uses General Motors Vortec 6000, 6 liters (365 cu. in.), 297 hp @ 4,300 rpm, 372 lb-ft @ 4,000 rpm, and GM Hydra-matic 6L90 double-overdrive 6-speed automatic transmission, same axles/suspensions and brakes, 16-foot van body.)

Tom Berg holds a commercial driver’s license and does Test Drives of all classes of trucks. He also writes about vocational and medium-duty trucks, trailers and bodies, maintenance, and alternative fuels.

Comment On This Story

Name:  
Email:  
Comment: (Maximum 2000 characters)  
Leave this field empty:
* Please note that every comment is moderated.

Newsletter

We offer e-newsletters that deliver targeted news and information for the entire fleet industry.

GotQuestions?

Sleeper Cab Power Experts

The expert, Steve Carlson from Xantrex, will answer your questions

View All