I'm considering an upgrade from my x350 to the x351. ( early x351s like 2010s)
As I'm very very happy with my x350, I don't want to loose this happiness, therefore I'd like to know:

- anyone tried (chinese) mongoose with SDD on a x351 ?
- where to get the service manuals ?
- is there an big service required at a certain milage/age ? (maintenance sheet ?)
- is the x351 as quiet inside as the x350 ?
- does bluetooth/nav work work stable or does it crash/lock up ?

nebelfuerst, not having ridden in a X350, I can't speak for the sound difference between the two cars, but the X351 is pretty quiet.

As for the bluetooth/nav, I have a 2012 which has the upgraded screen and I have not noticed any lag in the unit. Granted, the 2010/2011 units were not necessarily slow/lock up, but the screen would not always respond promptly to a press with the finger (ie, it would take a few seconds before it would do anything). The only delay that I get with my radio/NAV is upon starting the car. I have a 16GB memory stick in the usb port for all my music. So, it takes about 10 seconds for the car to get started up and then sort through all that music before I hear music. I will get the back up camera after about 5 seconds.

As for the SDD, I am getting ready to test a setup I found using a SDD from a british supplier and i had a mongoose cable from another project I had. I will try and let you know how that comes out.

As for service manuals, unfortunately, these are hard to come by as they are mainly controlled by the dealerships. With that being said, you can subscribe to a service like ALLDATA.COM and they will give you access to a manual that you can look at online. BUt, the subscription will limit you to a single year vehicle and if you want a second vehicle, that will cost you slightly more.

As for a service sheet, let me see what I have in the way of information. I may have a service manual that will say what is required when. BUt, I would say that you can plan on a fairly intensive maintenance period coming at 100K miles (160,000KM). This is when the spark plugs need to be changed and they will normally also say the tranny fluid, coolant, and a host of other things need to be done.

I test drove a X351 and the car felt big, hard to park, u-turn or see out, a bit firmer and 'sportier' than my XJ8L. You'll not get the 'rolling in a cloud' feel of X350's air suspension. So if that's your single favorite X350 feature as it is mine, then you would not be happy with the newer car.

High mileage should not be a deterrent. My car has 120k mi and all the expensive parts/brakes/air struts/etc. replaced/upgraded. Lucky buyer should I decide to sell.

But I decided to keep my car after the test drive.

- anyone tried (chinese) mongoose with SDD on a x351 ?
I haven't, so I'm not sure about secure access, but for troubleshooting it should work. I would highly recommend using a licensed and patched copy of SDD to work on the X351 if you intend to flash anything.

- where to get the service manuals ?
Subscribe for access to the workshop manual here: https://topix.jaguar.jlrext.com. You can use a PDF printer (I use CutePDF which is free) to save copies of any workshop manual sections you want to keep. You should be able to grab everything you want in a day. (An hour would be pushing it.)

- is there an big service required at a certain milage/age ? (maintenance sheet ?)
The service checklists are available on TOPIx (you need to enter the VIN to download them). The services are the same as the XF. Diesels are every 16,000 miles or annually, and the petrols are every 10,000 miles or annually (15,000 for the 5.0 petrol). A brake fluid change is recommended every three years, but you should test the fluid for water content annually and only really change when it needs it. Items like seat filters can be changed whenever they actually get dirty rather than to schedule. Servicing costs have not been any greater than with the X350s for me.

- is the x351 as quiet inside as the x350 ?
My diesel is quite a bit quieter. The glass is different and the insulation is greater than the X350s.

- does bluetooth/nav work work stable or does it crash/lock up ?
2010-2011 the system is slow to respond to touches and is frustrating and IMO dangerous to use.
2012 seems to have the same system at the start, and a better system at the end.
2013 onwards has a faster system that is easy to use. Some people report the sat nav entry screens as slow, but I haven't found them to be a problem.
BT works fine on all years though. It is possible to upgrade the earlier slow screens by replacement if it bothers you too much (see the link in my signature for the discussion thread).

Maybe so with the XJL, but I don't find my SWB XJ to feel any bigger than driving my XKR. Plus, my XJ is way easier to see out of than my XKR (unless I have the top down) and it's also easier to park since my XKR doesn't have a rear view camera. Honestly, my XJ is as much fun to drive as my XKR - 470hp in Dynamic Mode is a HOOT! Plus, it's gorgeous!

Thanks a lot for your feedback.

As I like to drive my car quite fast, I'd like to ask, how the brake assist works.
Does it recognize an obstacle and brake automatically ?
Or is it just an amplification of brake force, when hitting the pedal quickly ?

According to Jaguar owner info, brake assist only works (1) in conjunction with forward alert and adaptive cruise control, AND (2) when you hit the brake pedal, regardless of force.

"Advanced emergency brake assist (AEBA) is available at speeds above approximately 7 km/h (5 mph) and improves braking response during emergency braking, when a moving vehicle is detected close ahead.

If the risk of collision increases after the FORWARD ALERT warning is displayed, advanced emergency brake assist is activated. The brakes are automatically applied gently in preparation for rapid braking (this may be noticeable). If the brake pedal is then pressed quickly, full braking is implemented, even if only light pressure is applied to the pedal.

The system may not react to slow moving vehicles and will not react to stationary vehicles or vehicles traveling in the opposite direction.

It will not warn you before applying AEBA if the distance to the vehicle ahead is very small or if steering wheel or pedal movements are large (e.g. to avoid a collision).

Braking performance will only be improved if the driver applies the brakes.

AEBA uses the same radar sensor as ACC and Forward alert

Advanced emergency brake assist will function even if Forward Alert and ACC are switched off. If there is a fault with the system, FORWARD ALERT UNAVAILABLE is displayed in the Message centre. The vehicle can still be driven and the braking system will still operate, but without advanced emergency brake assistance. Consult your Retailer/Authorised Repairer to have the fault rectified."

I test drove the XJ in 2012 when it was still new. I heard the later MY2013 softened up the suspension a bit.
A few weekends ago I went down to the dealership to drive the F-Pace S and a '15 XK. Very nice cars, both of them, with the F-Pace S edging out the XK in ride quality and nimbleness. Then I got back into my car and proceeded to ride the air cushion home. It gave a serene feeling of luxury and comfort that the new Jags just do not have (all feel edgy and 'sporty')
I'm keeping my old car indefinitely and buying a CPO F-Pace in a couple years.

Some excellent feedback for X350/358 owners but one notable omission is whether the X351 has the air suspension weakness of the earlier model. Any info on failures, replacement costs, aftermarket solutions?