December 8, 2011

Fuel and horses – Wrangler's new engine

Probably the most anticipated change to the Jeep Wrangler since the introduction of the current JK was the new Pentastar 3.6 litre V6 engine. Chrysler's new "hero" V6 will be widely used across its product range. 4wdNewz has already tried the Pentastar in the Grand Cherokee and Dodge Journey. It endowed the big Jeep with performance not much different from the Hemi V8, an impressive accomplishment. I've now had a chance to drive a Pentastar-powered Wrangler Unlimited on- and off the road. Although it's a good engine, I'm not sure it deserves the rapturous publicity afforded it by Jeep publicists and some motoring writers.

It all fits nicely, but there's not much spare room.
Note the air intake lower centre.
The new motor produces some 40 per cent more power, at 209kW, than the outgoing 3.8, but torque is up by only about 10 per cent to 347Nm, which is really neither here nor there. I was expecting the new Wrangler to really bolt, given all those extra kWs, but although it's undeniably quicker, it's nowhere near as "quicker" as the 40 per cent figure suggests. On the road, it knocks a couple of seconds off the 0-100km/h time, but when you think about it, that's not really a lot: "One-Mississippi, two-Mississippi." That's all. More usefully, its overtaking times are better, a safety enhancement. Driving some of the new tracks at the Jeep Woodhill 4WD Adventure Park I found no off-road advantage compared to the 3.8 in my two-door Rubicon. Except for one thing:

14.8 overall, including off roading!
As part of the package, the Pentastar comes with a new five-speed automatic transmission. This adds a ratio over the old box and manual tiptronic-type changing for when that's an advantage. This engine and gearbox combo provide outstanding fuel consumption compared to the outgoing model. After a session in low range, my 3.8/four-speed would be recording something like 19 litres per 100km, maybe more. After what I considered a reasonably hard workout, the Pentastar would do no worse than 16.5! This advantage is also apparent on-road, where it routinely saves around 2.5 litres per 100km compared to my 3.8 JK, despite the two-door being lighter than the Unlimited.


  1. Interesting report, thanks. I've been seriously considering an Unlimited or an FJ Cruiser. Which would you suggest?

  2. Up to you, Anonymous. Enter FJ Cruiser in the Search panel at the top of the page and you'll find some comments that might be useful. Personally, I wouldn't buy either, but only because I'm a fan of short wheelbase two-doors.