Hey everyone,

I recently became the owner of a Jaguar XJ X351 and would love to hear from others with experience on this model. A few things I’m curious about:

• Performance: How’s the driving experience with the V6 vs. V8? Any noticeable differences in power or handling?
  
• Maintenance: Any common issues to look out for, or tips for long-term reliability?
  
• Upgrades: Anyone done mods to enhance performance or comfort? Any must-have accessories?
  
• Fuel Economy: What kind of mileage are you getting, and any tips for improving it?
  

Looking forward to hearing your insights!

Thanks,

 

If only this were real. The only alternative is to read thru all the threads here like the rest of us.

 

Mazda99, welcome to the Forums. Lots of good information here. We strive to be a better car group than what you are going to normally find. I think you will find the atmosphere here very easy going as we like to get to know one another. With this, we ask that you stop by the "New Member" section and give us a quick intro of who you are and what brought you to Jaguar. This will also give you a chance to meet those that make this place what it is.

Now, for your questions.

Performance: This is a very loaded question as some find the performance more than adequate. Others, well, they are pushing the limits. So, is the 340/360 hp of the supercharged V6 enough for you? This is far more power than most cars on the road have. So, getting around people is not a problem. For some, this is not adequate. If that is the case, you can chip the V6 and replace the supercharger pulley to get it up to around 420 hp. But, you do not want to go much beyond that as the transfer case from what I have found is limited to around 458 hp. This is why you will not find any supercharged V8 cars that are AWD. Now, members are pushing their V8's up to around 620 hp which is now starting to reach the limitations of the transmission. Again, this is nothing more than normally a tune and a new pulley. I have owned a naturally aspriated V8 (385 hp) and a supercharged V6. I personally like the simplicity of the NA V8 and the low end torque that it had. Now, do not get me wrong, the V6 will hold its own and if you roll into the gas, the V6 will hold and gear and pull you all the way from 20 mph to 80ish in a nice long hard pull. So, in short, yes, you are going to have variations in straight line speed. The one advantage I will give the V6 is that it has AWD and if you like twisties, the AWD is going to be what you like. With both the V8 and V6, I would normally get around 28 mpg on the highway. I find that the car really likes to cruise at about 85 mph and you can start to get the mileage up to around 30 then.

Maintenance: Save a $1000 USD right now!!!!!! You will want to invest into the upgraded aluminum water pipes and the latest version of the water pump. If the kitty has an achilles heal, it is the cooling system, specifically the plastic tubing it uses. You do a search on cooling issues, you are going to find a ton of horror stories. If you do have a water pump issue, TURN THE ENGINE OFF IMMEDIATELY!!!!!!!!! You overheat the engine, you are looking at a $30K+ repair bill to replace the engine (aluminum heads and block do not like being overheated and will warp in a heartbeat). If there is a second problem, I would say it is the fuel injectors. You get any dirt/crud into the fuel, these will plug up and give you all sorts of grief. Unfortunately, they are $200 each, it is recommended that you at a minimum replace all the injectors on one side of the engine, if not the whole engine. You can see where this can get expensive really fast just in parts.

Upgrades: I wish you luck. There are very few and most of what you are thinking, you are going to have to do something custom (ie, big dollars) to get what you want. For the motor, you have a cold air intake, performance chip/tune, and a pulley. Beyond that, you first have to find someone willing to gamble wtih the Jag, then pay them to experiment. Most exhaust work is something custom. But, most of what you are going ot change is the sound, not so much change the power (unless you have done other performance enhancers). Jaguar did a pretty good job on the factory exhaust for maximum power. If you have something specific in mind, ask. Someone may have done it. If not, you are treading in new water and we ask that you tell us how it went so we can decide if this is something that we would want to contemplate. The one mod I have done is installed a dual USB port into the faceplate of the rear console. This allows me to charge 2 USB devices at 2.1 amps each. They are like $12 on Amazon and wiring it up is 2 wires. Very simple mod.

Fuel economy. If you drive a lot in town, your mileage is going to be 15-18 mpg. These motors really do not like slow speeds. You get the car up to 75-85 mph, then you can get 28-30mpg. This all assumes you have the NA V8 or the V6. The S/C V8, you can plan on being 1-2 mpg less unless you like the loud pedal, then you are probably not worried about mileage. As for improving it, I know a lot of people are going to hate this, but you need to keep the stop/start feature (this is something a lot of people get rid of in their cars due to the number of starts a car goes through on a normal in town run and this will most likely be something you will be looking to turn off). After that, learn to let the kitty coast. You wlll find that gently pushing on the gas to let it shift at 2500 RPM will be plenty to keep up wiht other vehicles and will not push the engine into hard use of fuel. Granted, it is always fun to put your foot into it and let the kitty leap. But, the mileage will tell you about it.

Please give us some more stats on your car. For example, how you disable the start/stop feature varies based on the year of your car (10-12, didn't have the feature, 13-15, you had a separate battery that you can disconnect, 16+, you need to get a computer chip to disable it). There are minor changes that were made through the years, so, knowing what year and engine you have is going to help ensure you get the needed info.

 

Mazda99, One more important item. You will find engine oil changes are simple since it can all be done from the top of the engine. If you do your own, invest in the vacuum pump system that sucks it out. Of great importance, however, is adhering to the oil specified for the x351 engines. That oil has been designed for these engines. Do not use any old off the shelf 0W-20 oil. There are just a few brands that meet the JLR spec and look for that on the container. Castrol is the Jag specified oil but others meet the spec. You will find Castrol EDGE Professional 0W-20 difficult to locate other than at the dealer but most of us have found a source for the precious spec oil. Read your manual for the JLR spec. Most of us change our oil in the 5-7K miles range and do not believe it is healthy to keep the oil for the extended time you will read about.

 

You got some great replies from the above experienced Jaguar owners!
But as posted there is no simple answer and this forum holds an astounding amount of information if you look.

What your missing is you are the biggest factor in all of this. Can you DIY the car repairs? If not plan on a very expensive ownership.
Maintenance is the key so get familiar with all the fluids your car uses and change them REGULARLY!

And do post some pictures of your car as we ALL love to see them!
Hope you enjoy your time here.
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What year do you have? Some issues were worked out after 2014 or so, and anything after that is generally very reliable.

I've had an XJ and an XF, both with the same V6, both awd. For the most part, all great, and I simply swapped them at age. I had a V8 for a week, and it was lots of fun but too much for a limo imo, so decided the V6 was fine and fast enough for my needs. The most common issue I think is the coolant lines that run between the engine and supercharger, which will age and crack (you'll smell it before they go), and water pumps.

Performance wise, the car will understeer like a pig on ice if you're not gassing it through a corner, but on highways it simply eats miles and illegal speeds are nothing to it. The steering and throttle are 'aggressive' given the type of car, but that is the type of liveliness I like - the car feels sporty relative to an S Class, 7 Series, etc.

I get 20 mpg in town on premium, which I'm fine with. As for upgrades, I dunno - I bought one that came with just about everything already, so not much I'd want to add. The infotainment is probably the weakest part of the XJ experience imo, and its not really bad, just clunky.

 

rothwell sorry but I forgot to say "Well Done!"
Love that Cliff's notes version! Did you make that?
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Mazda99 - you have received great answers already. IMHO the V6 is more than enough power and is smoother. Open the hood before every drive to check the coolant or replace with all metal coolant pipes. I get just over 30 mpg, but I drive slow. Listen to the Thermo and Clubairth1 and the experienced listers and you can't go wrong. Its almost Lexus like reliability IF you learn what you need to do - and replace your valve cover gaskets at the beginning if they are even slightly leaking. Great car. Jaguar was mad to have stopped making it.

 

Hi Saki,

I've just been looking through some threads as a new XJ owner. Mine is in green which I thought was the best colour I've seen - before I saw yours!! Absolutely beautiful....

 

I had the thermostat housing crack at the seam and the expansion tank float got waterlogged. Otherwise fine at 30,000 miles. 2019 XJL.

 

Cooling system failure at 30K miles is insanity.

 

The 2019's have seamless plastic pipes, but the thermostat housing still had the seam. They replaced mine with a Land Rover seamless housing. It seems to be fine now.