I've read of some people who seem to be getting pretty good MPG, especially on the highway, with their S Type R's...

I'm getting less than 300 MPGs on a full tank (at least that's what the on dash is telling me)...and probably 16 MPG combined with an equal amount of city/highway driving...

I'm already looking into new plugs, but if anyone has any other ideas (ie K&N filter), I would love to hear them...

TIA...

 

Use a calculator to get a true figure. Fill at the same pump. Stay with OE filters. They work, with no issues, and they're affordable.

 

Get a cold air kit or K&N, check your tire pressure, winter gas mix sucks and loose a few miles per gal....Any do like jagv8 said is check what you actually do at the pump per fill up......

 

Dunno about mods to increase mpg on petrols but I've had several diesels chipped to increase bhp and torque giving excellent performance AND achieving 10%-15% fuel saving when driven normally!

Dunno if you seen the Audi A8 diesel trip from London to Edinburgh AND back 800 miles on one tank of fuel?
https://www.jaguarforums.com/forum/s...highlight=audi
Simple tips such as
NOT carrying the world around in your boot / trunk
Don't drive with the window down - creates drag
Wherever possible - Don't use A/C as this can reduce fuel efficiency by 6%
Don't brake / speed up unnecessarily etc etc


All basic stuff I know, so please don't be offended. Other than that making sure your tyre pressures are correct, cars in tip top shape and drive sensibly

As per Jagv8 - by all means use the trip recorder to guage consumption but do a manual check too to compare!

In my 2.5 V6 X type I could get anywhere between 250 miles and nearly 400 depending on how I drove and the combo of urban / highway driving....soon mounts up to a few $$$

 

mine is stock, with k&n filter, just filled up this morning. 26.5 mpg. 345 miles and used 13 gallons almost exactly

 

I get @315-320 per 14gal ish....but it is all in town driving pretty much w/o stomping on it too much.....rarely going over 2500rpms unless some unlucky rice gets next to me for a second

 

Thanks for the replies...

I do all of the typical maintenance in regards to tire pressure, oil changes, filter changes, etc...

I'm going to switch the plugs out to NGK Laser Iridiums and order a K&N filter as well as look into an intake...

Is there a forum vendor anyone would recommend for the K&N???

 

Doesn't your STR already use iridiums? How many miles on it?

 

Getting ready to turn 77K on the ODO...

So all Iridiums are the same???

 

wouldn't porting the supercharger technically improve mpg since more air is moved inside for combustion for efficiantly. I mean the horsepower gain is there, and stepping on the gas would be a big lure, but shouldnt it improve mpgs if driven normally?

are you getting ur new iridiums from eurotoys? if not were else are you checking because im thinking my car is 7 years old now and still has the stock plugs, only 40k on the odometer though

 

Different spark plugs will not affect HP or MPG. A spark is a spark is a spark. The iridiums are used for extended lif, not for performance reasons.

 

390 - I am not sure whether they're all the same but I think the STR uses Denso (same as the PCM) and they make good stuff. I doubt the NGK are any better but maybe a tech will comment.

TT - you're kidding, right?!!! You want more efficiency? Probably would mean being leaner. You're gonna shorten engine life, aren't you?

Mikey - sorry to disagree but it's for the way the spark functions, too.

 

I'm actually getting the Iridiums through my independent service shop...they matched euro toys and summit racing's prices without paying for shipping...

I'm surprised there aren't many ECU reflash(s) floating around for this engine, especially since it was sourced from Ford...most flash's improve MPG as well...

 

I was just told that NGK is the OEM plug...maybe just as well, I've heard of issues with the Denso...

And you're right, the plug can definitely make the combustion leaner and more efficient...I've heard up to a couple of MPG's better...

I also just ordered a K&N from Autoanything for $41 shipped :woohoo:

 

390 - the STR engine was not sourced from Ford!

And I don't think Ford even use the Denso PCM, either.
(But an occasional subsidiary company does, in smallish numbers.)

 

It barely has a ford part on the car let alone the computer.....I wish it was so I could have someone tune my STR!

 

Wellll, you can have that now... Arden do it or someone

And if you get hold of a tuned PCM can't you figure out what they did? (More likely: get someone else to figure it out.)

 

I thought the 4.2 was sourced from Ford...didn't know it was a Jaguar original...

 

wikipedia's pretty good on it see AJV8 engine

 

Absolute myth, but believe what you want. OEMS spend millions of dollars trying to squeeze every MPG they can out of an engine. Why would they not simply use these marvellous plugs instead?