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Andrewbg86 09-22-2016 09:26 AM

Hello everyone!

I'm new to the site, I don't know how I've never come across it before, it's a great resource!

Im a great fan of Jaguars, but Jaguars and economy don't really go together. My old v12 Jag does 4/5 mpg (uk) and with fuel here in excess of 5 a gallon it's not a cheap car to run.

My every day car is a 2006 Jaguar X Type 2.2 diesel, and as I already spend far to much on fuel in some of my other cars, I've been trying to save a bit in my every day car.

The factory says the car will do 47mpg (uk) combined. By driving carefully I was able to get upto 50 mpg.

I've started doing a few modifications to try and improve things further and had some good results, the last few tanks I've been just over 60 mpg (uk)

I've been doing things on a tight budget, the idea of this car is to save money not spend it.
So this is the story so far

Car was purchased for 950 needing a few flywheel and a few other bits.

New fly wheel, clutch kit and brake discs and pads all round purchased for 450

The car had some nice big wheels on it which I sold for 325 and i put some narrower wheels on which I had in stock.

The aux belt and tensioner needed replacing, on this ending the aux belt drives the air con and alternator from the crank pully, the belt had a tensioner and two idler pulleys. The air con pump was removed, and the alternator bracket modified, and a stretch fit belt now drives the alternator from the crank with no idlers or tensioners. Saved weight, friction, saved money on the tensioner kit and sold the air con pump for 70.

I then removed the catalytic converter and which I got 170 for and replaced it with a 30 decat pipe, and removed the EGR valve which I got 45 and replaced that with a 20 egr removal pipe.

I have also removed the air intake pipe which channel end the air in from the front grill to the air box. This pipe was quite restrictive, now the air is taken from a much bigger area from much behind the radiator, the engine now breathes better and the air intake temp is about 3 degrees c warmer.

The car also has a hydrogen fuel cell, I've not seen anything about them on here yet, but it basically turns water into hydrogen and oxygen using a bit of electric, this is supposed to improve the fuel burn increasing economy. It doesn't save the amount of money the people who try to sell these advertise, but my feeling is that it does something. I had this system on a previous car, thought I way as well reuse it rather than binning it.

So todate, the costs, including the cost of the car, minus the bits I've sold off it have cost me 800, and I'm getting 60+ mpg (uk) which I'm fairly happy with.

I'm not wanting to spend loads of money, but if anyone has any suggestions of other stuff I could do, without breaking the bank, let me know.

I'm not really into sacrificing power or comfort in the pursuit of economy as I do quite a lot of miles, but todate, with the current mods I've noticed a fairly good power gain as well, so I could live with loosing a few BHP.

In just over a week I'm due to do a 2500 mile round trip in Europe so it will be very interesting to see how the car performs.

MetroMPG 09-22-2016 10:21 AM


Sounds like you're having fun with the project.

The logical next step, especially considering impending highway use, is to improve the aerodynamics.


- partial grille block (assuming you have an accurate way to monitor coolant temp)
- remove/relocate the passenger mirror to just inside the glass on the A-pillar
- test an air dam (sometimes they help, sometimes they hurt)
- and/or smooth undertray
- smooth wheel covers
- tire spats/deflectors
- etc.

Do you have any options for re-gearing the car? A taller final drive or top gear would probably help as well.

Andrewbg86 09-22-2016 11:18 AM

I should have mentioned, the reason for starting with the 2.2 rather than the 2.0 diesel is the 2.2 has a 6 speed box rather than the 2.0 5 speed. 5th gear in each car is almost the same, and so 6th does help with economy. I did consider starting with a 2.0 and putting the 6 speed box in it, which would give better economy, but this came 2.2 came up at a good price so here we are.

I have blanked off the front grill already, I just shaped a thin bit of aluminium to fit the grill at the back, not totally air tight but it's all I had to hand. What materials do other people use to blank off a grill? Do you go for a perfect air tight fit?

The car has an engine under tray as standard, and after that the under side of the car is relatively flat, until you get to the axle, so I'm not totally convinced that a bigger undertray will do much.

As I do some driving in the uk and some in Europe, (some driving on the right and some on the left side) sadly I don't think removing a mirror is a viable option.

Tire spats are something I've not thought about though, any tips on designing and making them?

mcrews 09-22-2016 11:23 AM

raise the psi in the 'tyres'.
we run over 40psi in the states.
also, when you go to buy tyres again. go 1 size taller(same rim size). that will lower the rear ratio and help w highway mileage.

Andrewbg86 09-22-2016 11:37 AM

Thank, I inflated the tyres to 42psi. 8psi more than recommended. I have been told that if you go too high your tyres don't last as long, so worried it might be a faulse economy. What's your experance of this?

I will defiantly go for a slightly higher tyre wall when it comes to renewing the tyres. As it's had some slightly smaller wheels on, the speedo is actually reading slightly slower than it should, and of course the miles covered will be slightly less than it should. So increasing the tyre hight will rectify that problem as well as helping the mileage. The narrower tyres (205 wide instead of 225) have defiantly helped with efficiency though.

mcrews 09-22-2016 05:30 PM

I ran stock 245/45/18 on the 02 Q45S.
then went taller, 50 side wall. was worth about 3mpg on the road. I did a lot of highway driving. They were also a little narrower.

the deciding factor on tire size was the bottom of the strut tower! ended up having about 1/3 inch gap:eek::thumbup:

MJamson 09-23-2016 04:23 AM

Nice to see another English person, welcomes.


Originally Posted by Andrewbg86 (Post 523292)

The car also has a hydrogen fuel cell, I've not seen anything about them on here yet

There are a number of posts about these in the unicorn coral.

You might want to reconsider the air intake as some diesels prefer lower temps. The idea of the warm air is to encourage petrol cars into lean burn mode.


Originally Posted by Andrewbg86 (Post 523292)
As I do some driving in the uk and some in Europe, (some driving on the right and some on the left side) sadly I don't think removing a mirror is a viable option.

The road regulations differ quite alot between Europe and the USA, so some mods that are mentioned on this site aren't legal within Europe, if memory serves me correctly (and it is going back a few years) you must have the drivers mirror and one other mirror, but if you are driving on the right side of the road you will certainly have more benefit of the mirror as apposed to the small fuel saving.

What state is the engine in ? I have had good MPG gains by doing a decent service and using a decent injector cleaner.

Daox 09-23-2016 10:35 AM

Welcome to the site. Nice job with the Jag.

I once had a 73 XJ12. Beautiful car. Mine needed work since day one of owning it, and unfortunately I never had the pleasure of driving it around. My wallet thanks me though. I later sold it to a car builder after it had sat around for many years of me not getting around to it.

mcrews 09-24-2016 07:01 AM

I drove a 99 Vaden Plas for about 2 years. VERY sweet ride. Oddly enough, I never and a bit of problem.
Got decent mileage on the road.

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