New models - Jeep - Grand Cherokee
First drive: CRD a Grand choice
Jeep's new turbo-diesel Grand Cherokee is a beauty, thanks to help from Mercedes
10 Mar 2003
By JOHN MELLOR
IN an early tangible development in the Mercedes takeover of Chrysler, Mercedes-Benz has become a benefactor of its country cousins at Jeep by making the diesel version of the Grand Cherokee a viable alternative to the Mercedes ML270.
The undisguised installation of the ML270's quite outstanding five-cylinder diesel engine in the Grand Cherokee elevates the Jeep flagship up the buyers' list of alternatives in luxury off-roaders.
The price of entry to this world of Benz via Jeep is a little less than $60,000. The Mercedes ML270 CDI is $10,000 more.
The same engine is also found in the prestigious Mercedes E270 CDI sedan that sells for between $90,000 and $100,000.
That such largesse by the Germans may ultimately prove to be their undoing is irrelevant.
For those who, for various social mores, cannot bring themselves to be a Benz owner, the more Gomer Pyle-ish Jeep brand can now deliver Mercedes engineering and a Mercedes driveline without the embarrassment of selling out their egalitarian values.
The diesel is a very good engine. Combined with a smooth Mercedes five-speed automatic, it adds a commendable dimension to the Grand Cherokee line-up to the point that it is probably the only Grand Cherokee worth buying.
For a start, the Grand Cherokee is built by Europeans (in Austria to be precise) and therefore is less likely to be plagued with the build quality problems that have beset the Mercedes ML, which is built in Alabama by less quality-focussed Americans.
Largely due to the ML, Mercedes-Benz warranty claims worldwide topped $2.8 billion in 2000, a threefold increase in two years, according to the Financial Times. In 1999 and 2000 the ML was ranked at the bottom of all US sport utilities for quality by the J. D. Power Initial Quality Survey.
So there is something appealing about a luxury Jeep built in Austria using an engine and gearbox made in Germany by Benz.
Add to that the edge that the Mercedes diesel engine has over the six-cylinder and V8 petrol engines made by Chrysler in Toledo, Ohio, and the argument is complete.
The Chrysler petrol six and V8 engines are pretty old technology, are a lot thirstier than the Mercedes engine and do not have as much torque or towing power.
The data tells the story:
There is not much in the pricing either with the diesel selling at only a marginal price premium over the six and just $100 over the V8. It is considerably cheaper than the V8 High Output package in the Overland.
It also sits under the ML270. Of course the Benz comes with traction control as standard whereas Jeep's version of traction control, called Quadra-Drive, is only standard on the Overland and a $2078 option on other models.
Standard features include multi-stage driver and passenger airbags designed to inflate according to the severity of the crash, ceiling-mounted curtain airbags front and rear, air-conditioning, six-way driver and passenger power seats, cruise control, remote keyless central locking, tinted glass, power windows, power accessory delay, six-speaker sound system with 180-watt six-channel amplifier, covered cargo area and infra-red interior security sensor. The four-litre six-cylinder petrol engine with four-speed automatic is standard.
The Limited gets infra-red dual zone climate control, 10-way front and passenger power seats with heating and memory, heated and auto-dim exterior mirrors with driver side memory, 10-disk remote CD changer, auto-dim interior mirror, leather-wrapped steering wheel, wider tyres with 17-inch wheels and rain-sensitive wipers. The 4.7-litre V8 with five-speed automatic is standard.
In addition to the above, the Overland gets the High Output 4.7-litre V8 engine, Quadra-drive anti-slip transfer case, rock rails for sill protection, wood trimmed steering wheel with radio and cruise controls on the spokes, and a sunroof.
The move to the Mercedes diesel is also timely for Jeep. BMW will launch a diesel version of the X5 within weeks.
Jeep Grand Cherokee Laredo 4.0-litre I-6 auto: $55,590
Jeep Grand Cherokee Laredo 4.7-litre V8 auto: $58,990
Jeep Grand Cherokee Laredo 2.7-litre CRD I-5 auto: $59,890
Jeep Grand Cherokee Limited 4.7-litre V8 auto: $69,790
Jeep Grand Cherokee Limited 2.7-litre CRD I-5 auto: $69,890
Jeep Grand Cherokee Overland 2.7-litre CRD I-5 auto: $74,890
Jeep Grand Cherokee Overland 4.7-litre V8 HO auto: $77,490
Drive impressions:OVERALL, the 2003 models are basically the same but Jeep engineers have also been playing with the suspension and the steering, eliminating much of the rubbery ride and lack of feel in the steering for which they have been criticised in the past.
Highway driving and winding country roads demonstrated a lot of the vagueness and feeling of imprecise road placement that plagued earlier Grand Cherokees had been overcome.
The brakes have been given a higher output pressure from the master cylinder. This and new brake callipers have increased the sensitivity of the brakes to light touching of the pedal. Drivers will need to get used to this to avoid unnecessarily throwing their passengers forward under normal braking situations.
Nevertheless, the four-wheel discs combine well with the more precise handling to give drivers more command over the prevailing road conditions with the anti-lock brakes proving impressive on loose gravel surfaces.
But the important story here is the Mercedes engine because the diesel engine and five-speed automatic package works so well.
The engine stands out for its very low diesel knock noise levels. This is achieved mostly through the use of a clever fuel injector that allows a small charge of fuel into the engine so that it fires just before the main dump of fuel is injected into the cylinder.
This, in effect, softens the normal clatter of the ignition of the fuel you get in normal diesel engines and makes the firing noise more car-like. Less knock and rattle.
At idle with the windows down you can tell it is a diesel but, other than that, is seems like a conventional petrol engine.
The importance of this engine is the performance it gets at very low engine revs. They key is torque - the twisting power of an engine that gives heavier vehicles that get up and go.
The more torque you have at low engine revs the better. Get good torque output over a wide engine rev band and it is even better still.
As you can see from the table above, in spite of its modest engine size, the five-cylinder 2.7-litre Mercedes diesel has greater torque that the six and eight-cylinder Chrysler petrol engines and, significantly, achieves this output at much lower revs and over a wide rev range.
Also, by channelling this twisting power through a five-speed automatic gearbox, each gear gets its turn of working in that maximum torque band as the vehicle gathers speed.
With fewer gears it would have to work across wider and therefore less effective rev bands in order to get the vehicle up to speed.
This gives the Grand Cherokee excellent around town and highway performance.
Even the power output is pretty respectable. While it does not have as much power as the petrol engines, that maximum power is achieved at lower engine revs and that also plays a role in its flexible highway performance.
The way they get this strength from so modest an engine is by turbocharging - blowing cooled air into the engine from a "hair dryer" powered by the powerful exhaust gasses leaving the engine.
One inherent problem with turbos is the cart before the horse syndrome. You have to get the engine spinning in order to create enough power in the exhaust to get the hair dryer going fast enough to give the engine extra boost. This produces "turbo lag" where, at low revs, the small engine is not getting its turbo hit and therefore takes a long time to increase speed in response to the accelerator.
Mercedes overcomes this problem with what it calls a variable geometry turbo (VGT). This means that at low revs the hair dryer uses massive vanes to drive lots of air into the engine to boost its twisting power. But, as the engine goes faster, it can generate too much boost from the hair dryer because it is now spinning these big vanes too fast.
Mercedes engineers, however, use a sensor that increasingly opens up these turbine vanes driving the air into the engine so they become progressively less effective but still deliver the right amount of boost to each cylinder.
This all combines to create more than acceptable performance in what is a large vehicle plus commendable fuel economy.
There are benefits off-road as well.
Such is the lugging power of the diesel at low revs and the response from even minor touches of the accelerator, it can be edged up steep pinches in the bush and eased over stumps and rocks almost at idle without losing power or traction.
Equally important off-road, engine braking for inching down loose or slippery slopes without touching the brakes holds the Grand Cherokee well under control.
The five-speed gearbox works well in low range, allowing quite reasonable speeds along tracks in fifth right down to super-crawl in first. Pulling the selector down into first is achieved with smoothness and precision, unlike the Chrysler gearbox in the normal Cherokee that grabs as though you have come to the sudden end of slack in a tow rope.
But the accelerator was especially sensitive lurching over rough ground in low gear and low range, and needs a stronger spring for that off-road work.
In standard kit the Jeep 4WD system automatically sends torque or driving power to the front wheels when any wheel slippage occurs on the back driving wheels.
The optional Quadra-Drive goes one step further by ensuring that not only does it transfer the driving power to the front, it can also transfer driving power from side to side to each wheel.
Therefore, even though three wheels might be slipping, driving power is still being sent to the one that still has grip.
None of the test vehicles were Overland models and none were fitted with the optional Jeep Quadra-Drive system.
Yet the standard set-up performed admirably over some fairly challenging off-road tracks, although the tracks were dry and a downpour on clay surfaces may well have demonstrated the added security the more sophisticated Quadra-Drive system would bring to the equation.
At a little more than $2000 as an option, it would be wise insurance for the more adventurous owner.
Overall, the Grand Cherokee is a good sized package with plenty of room as a five-seater. The seats are really comfortable with loose leather cushioning. You still get the command driving position although the climb into the seats seems to be less of a task than in other more elevated off-roaders.
At highway speeds all is relatively quiet save for some wind noise.
The handling now makes it easier to live with and the diesel has to be the choice unless V8s are in your blood and you like spending money on petrol.
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