No body really knows. Most are just rumors. But the one rumor that I have heard is of a Cummins diesel, a three something liter V6... and if they are coming out with one, I wouldn't expect to see it until 2009.
They put a 2.7 or 2.8L diesels in the European version of the JK now. So if you are in Australia or elsewhere overseas, you could get one now. There is only internet chatter stating there may be a JK diesel for 09.
They stopped producing the I-5 CRD for the Liberty, but there is hope as Jeep is now selling a V-6 CRD in the Grand Cherokee. So as long as they have at least one model with a feasible diesel option, there is hope for a diesel in a JK...
I think they stopped producing the I-5 CRD because of the '07 Diesel emissions. You'll notice VW also stopped all TDI production state side for '07. If they could get the little Cummins crammed in one it would be nice. Sometimes you can luck into a nicely done one on ebay, someone will drop an I-5 in a Wrangler.
From Diesel Power: The new Cummins diesel is a 4.2L (256ci) V-6, the V-6 is rated at 270 hp and 420 lb-ft of torque, 22 mpg in a test Durango.
It would be fun. Little jeep, light weight, lots of torque, chances for lots of HP on the cheap, lots of black smoke
diesel is most likely only for out of US market jeeps, whenever you hear of a car going into production and the company lists a diesel engine along side a standard, the diesel never gets released in US
Thats not always the case. Jeep has be dabbling in the diesel market, the Liberty and even the Grand Cherokee had a CRD diesel motors. Although those were Benz engine and Benz is no longer a major art of the Chrysler family, Jeep is looking elsewhere for their diesel fix, and with Cummins being a Dodge partner since the 80's(?) it would be a great match, especially since they recently released a new 4.2L V6 diesel.
so then why didnt they keep the 4.0L that was in the tj? better mpg?
Chrysler uses the 3.8 in other lines of vehicles and it also gets better MPG. So they killed two birds with one stone in retiring the I6 that was only used in the Wranglers. They do have a new 4.0 V6 that puts out better numbers and I think you'll see that option in the JK way before the diesel.
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I dont think a US diesel JK is very off and I definitely would not rule out 2009. People are jumping all over the MPG & biodiesel hype and Jeep is trying to appeal to a larger customer base by offering both a 4-door and a 2wd 4-door
There is definitely room for Dodge to pass its relationship with Cummins down to Jeep. The 2006 SEMA show had a diesel powered Unlimited and Jp Magazine (print edition) is spreading rumors of a Cummins diesel for 2009. I think Jeep is seriously considering it for the US market. Cummins is offering the 4.6L V6 for Dodge's light-duty applications, so it would not be unheard of for it to find its way into an Unlimited (probably at close to $35K-$40K).
the downside to a turbo-diesel in the offroad world is a lack of RPM's(my I6 CTD redlines at 3300 rpm). Granted they are getting better and there is an aftermarket for that fix in the pickup truck world. There's a lot of talk in the diesel world about diesel power getting popped into a lot of different things right now.
The Bio stuff is nice, but kind of hard to comeby and over priced around me(I'm not driving 45 min out of the way to spend $0.20 a gallon), also involves more filter changes. I'm a believer in the Big C (Cummins), if they drop a motor in one it will be a nice set up. But real world, I'd say a jeep w/a diesel would be 2010 or later after the new emissions standards are changed again, the little CTD's are hitting the 1500's and Durango's in late 2009.