Where I am diesel is now up to 7p per litre more than petrol. I do about 8000 miles a year. I would guess I get 10mpg more than say the 3.0 petrol.

Is it still worth it?

 

Delta66,

I would convert the price to price per gallon so you can divide using gallons.

For example;

Petrol at 25 mpg

8000 divided by 25 = 320 gallons required

Diesel a 35 mpg

8000 divided by 35 = 228 gallons required

Multiply by price per gallon.

(math was not my strongest subject)

Mike

 

Maths was not my strongest point either.

8000 miles divided by 30mpg (my diesel average) = 266.6

8000 miles divided by 20mpg (guessed petrol average) = 400

Price per litre diesel 137 x 266.6 = £365.24 worth of diesel

Price per litre petrol 132 x 400 = £528 worth of petrol

Looks like even on those guesstimates, based on the mostly short journeys the Jag does and equivalent for the petrol, it is still worth it.

Thanks.

 

This is the sort of reasoning that car dealers don't want you to do :-).

I penciled out what it would cost me to use my XJR for occasional pleasure use and buy something more economical for daily use.

XJR/baseline
2000 miles/month @ 18mpg average= 111 gallons. 111 gallons x $3.75/gallon = $416/month in gasoline expense.


What if I bought a economy car for daily use and drove the Jag only on weekends?

Decent used economy car, 28 mpg average:
$5000 purchase price + $500 for typical after-purchase used car fix-its = $5500

1800 miles @ 28mpg average = 64 gallons @ $3.50/gallon (regular fuel) = $224/month in gasoline expense.

200 miles @ 18 mpg (Jag/weekends) = 11 gallons @ $3.75 = $41/month

$41 + $224 = $265/month gasoline expense.

$416 - $265 = $151/month in gasoline savings

Cost for minimal insurance on a second car = $50/month

$151 (gas savings) - $50 (insurance) = $101/month net savings

$5500 (purchase price)/$101 month (savings) = 54 months to break even :-)



Of course all of the above is predicated on *keeping* rather than *replacing* my Jaguar. I simply cannot be without a Jaguar. It won't happen!

One alternative would be to buy a more modern Jaguar that would give better fuel economy, thus allowing me to run just one car. Perhaps I'll browse the S-type section and see what kind of fuel economy I might expect.

Cheers
DD

 

More and more people here in the UK asking that same question now Delta.
Factor in higher running costs when injectors etc go bad, etc etc.....its not the same saving it used to be.
The UK govt has seen to that......LPG will no doubt be the next target over the coming years

 

i think that S type 2.7L diesel,twin turbo, would make an excellent commutor vehicle.

with some small mods, like catylic remove, DPF remove(if it has one).

then a remap of ECU, i think it would improve fuel mileage by 10-15%, with more power to boot.
YES, would make a decent drive!

i wonder if i could buy one in USA, left hand drive??

RON

 

for now my daily driver is a 1982 OPEL-ISUZU diesel coupe, gets around 40-42mpg,US gal.

i burn used cooking oil blended with diesel fuel,25% to 75%, runs great.

now this gets interesting here, last month diesel cost was $11.74, cookin oil for free.
so my fuel bills become not important.

wifes car costs around $30. per week.

but diesel Jag would be a great project, a learning experience.

 

Remapping is an idea. Jim have you done that successfully? Is it worth it?

 

Hey Delta,
remapping is an excellent way to go, but dependent on mileage really for payback. The more miles and longer you own the vehicle obviously the quicker and bigger the payback.

I'm not 100% sure about the Jag but a diesel engine is a diesel engine.

I've done this on several vehicles now including my Audi A6.

I remapped a Saab 93 1.9 Tid Vector Sport from 150bhp to 175bhp and got great torque gains as you'd expect, serious improvment to power delivery, with a smooth response AND mpg improvement in the 10% - 15% range as was estimated.

I also remapped a Ford Mondeo ST Tdci 155bhp to 195bhp ( same Duratec engine as the X type I believe ) got great power improvement ( seriously quick car when needed!!! ) and the mpg WHEN DRIVEN NORMALLY was also improved by around the 15% mark.

Costs depending on where you go usually around the £300 - £400 range for a good one!

.

My A6 on a run from Glasgow to Derby at 75 mph for 99% of the time on cruise control, with a few blasts at 100mph+ as I was running late. I picked up a workmate and headed to South Wales and back to Derby, around 680 miles with 40+ left in the tank before I filled up and headed onwards back to Glasgow. When I did fill up the DIS told me to expect 915 miles if driven in the same manner!!!

I was trying to check on fuel economy ( but not that hard )
The boot was FULL of work equipment, fairly heavy too.
I had a 6'6" guy weighing arounf 17 stone in the passenger seat.
A/C on the whole way as well as numeruous electric devices plugged in and the window open slightly as I smoke........ALL fuel economy killers in their own way....so I was amazed!

Me personally? I'd be looking to do this on pretty much any deisel I ever buy

 

Sorry to spoil your dreams but the common rail, piezo injector equipped 2.7d Jaguar engine wouldn`t take to running on cooking oil.

 

Mine had a tuning box (torque went down on std and engine light when being too enthusiatic) which was ditched for a remap (power up and torque up from 321 lbft to over 381 lbft no engine lights)
Also factor in to the cost of running a diesel longer service intervals, worth more when traded or sold privately as bigger market for diesels), cheap servicing (every other one is just an oil/filter and checks) = £26.10 from National tyres for oil/filter who used Magnetec same spec as dealers.
With prices of fuel increasing the market is going to grow for diesels here in UK as more ditch their petrols which are becoming too expensive to run and change over to diesels making their value even better when you come to sell in future years.
PS I only do about 8k too each year but was just lucky the car I was looking at was an LWB Sovereign with the extra std feature over the SWB ie picnic trays,rear DVD entertainment system,piped sift grain ruched leather, heated reclining front and rear seats,etc etc

 

Derdave,, in USA, there are some Chevy-GMC duramax diesels runnin a blend of 50-50%
used cookin oil and diesel ffuel with no bad effects, and they are hi-pressure PIEZO injector systems.

im betting that Jag 2.7D would handle a blend of fuels, course someone would have to step up and try it!!

its all about good maintinence and proper setup.

 

Is there such a thing as tuning to improve mpg as its main aim? The tuning I find is all about more power.

 

I could be wrong Delta, but any remap I've seen as you say is all about increased performance with 10% - 15% fuel economy improvements almost as a bi product

 

I went to a forum on the X350 models yesterday, and some pictures of a wrecked 2.7 litre diesel were shown as one of the possible issues with the diesel engine.

With this syndrome, the turbocharger oil seals start to leak engine oil into the inlet air passage, and in its early stages, this is partly used as fuel by the engine without the owner noticing. As the seals wear more and more, more engine oil is used, and at some point, the owner turns off the ignition, but the engine carries on running using engine oil, and in worst cases, runs away, uses up all the engine oil and then seizes up.

If the owner is not diligent in checking the oil level regularly the oil runs lower and lower, and eventually runs out, even if engine runaway does not occur.

This is not just a Jaguar issue, it applies to all high power turbocharged diesels. The only service or maintenance action that can be taken is regular oil level checks. Other action is to let engine idle for one or two minutes before shutdown after a long highspeed run.

Other issue mentioned was the DPF. Owners doing lots of short journeys have had to replace the DPF as regeneration has failed, and this is a very expensive item.

And finally !! The diesels have a cam belt, and also a pump belt and these need to be replaced. It takes a good workshop about 12 hours labour to do, and recommendation is to replace various wheels and tensioners, and other items like the serpentine belt etc, so not a cheap job.

So in overall cost of ownership, is the diesel worth it for low mileage owners, as it is only high miles that generate the really significant savings ?

 

Re economy
The guy whoi remapped mine offered both an economy remap or an all out performance remap.
With the all out performance remap I reset the trip with cruise speed set at exactly 70mpg by my GPS and after 10 miles of what looked like level road the trip computer read 52.1 mpg (thats UK mpg!!).
Just got back from a 300 mile trip from Nottingham to Jaguars factory at Birmingham (UK!) the Jaguar Daimler Heritage Museum at Coventry and back to Durham and averaged 43.2 mpg but that included city driving and hard accelerating at times on the motorway as well as cruising over 70

 

Fraser, when turbo oil seals start to leak(that almost never happens,with newer tech seals) you would have a lot of oil smoke that should be noticable to anyone who is aware of his vehicle. smoke would become visible long before a runnaway engine.

and if i owned a DPF equipped diesel ,it would be REMOVED, same with catylitic convertor, better performance and reduced fuel consumption.

NOW i have owned and worked with diesel engines for over 40yrs, and only seen one runaway engine, and it happened after a non-familier technician hooked up wrong fuel return lines, on a mechanical injected system.

i dont think its possible to that on electronic piezo systems.

and as far as belts, yes it would be better with gears or chains.

i just changed a timing belt on an ISUZU diesel at 180,000 miles(still looked good).

and costs should be close to petrol cost, belts.

 

diesel engines are quite simple, reduce fuel volume, reduces torque.

increase fuel volume, increases torque,(assuming same injection timing).

one thing that we dont like is PEAK torque occurs at peak smoke conditons,

in other words, if you aint smoking black, you aint making power, at full load,Acceleration!

this does assume we are using diesel fuel.
there are fuels that dont smoke, but there are NOT economical.

 

Mine doesnt smoke AT ALL both before and after the remap and IS making more than the std power
Made 52.1mpg (UK mpg) at constant 70 mph (set on cruise using GPS) over 10 flat miles
Torque std was 321 lb ft and now 382 lb ft post remap and thats with the DPF to meet emissions here in UK!

 

+1 on that Buck....no smoke here on my A6 with a remap too.
Just increased fuel economy when driving normally and more bhp / torque at my disposal......have also achieved around the 52.1mpg on a long run and 730 miles to a tank with display showing 915 available miles when refuelled