Happy with my MPG

[MATT'88]

Hi matt,

I put 52.5L when it said 10 miles left, its a 55L tank which is what i guess is what you put in for £58 of fuel.

When full, my car is saying 450-500 miles for a tank.

Half a tank for 160 miles is 360 miles for a full tank which is 40 miles less, or 10% than your 400 miles.

Sitting at 75 as opposed to 70 can use 15% more fuel, 80 can be 25% more! Ive not measured for this car, but as a gernal thing, most cars conform to that.

Wont have that problem with the FR!!

So why does yours say 500 and mine barely makes 400. I sit at pretty much 85 with cruise control. i cant remember what mpg says. i just feel its nearly as juicy as my old saxo vts which done 20mpg at best of time.

 

[stuartsjg]

So why does yours say 500 and mine barely makes 400. I sit at pretty much 85 with cruise control. i cant remember what mpg says. i just feel its nearly as juicy as my old saxo vts which done 20mpg at best of time.

Thats really going to hurt the econ so i cant blame the car for using so much fuel.
The computer bases the miles per tank on the journey MPG, higher MPG will show more miles per tank.

Also, if you are getting held up, say behind 65-75 people or 55-60 lorries then accelerating up, either by foot or cruise resume thats a killer for using fuel.

Constant speed burns fuel only to overcome losses.
Fuel burned by accelerating only gets dissipated as heat in the brakes when you come to slow down unless you avoid braking and roll in gear (move down the gears, go as low as 2nd before coasting)

Also, accoding to a series of detailed Which Car trials:

"On motorways, keep to the speed limit. Driving at 85 mph instead of 70 mph increases petrol consumption by 20-25%."

THis will apply to diesel too, its just moving the air out the way thats all the hard work.

Look at the Bugatti Vayron, needs 200HP to do the first 150mph, then needs 800 more HP for the next 100mph.

If you want to be technical,

Power = 1/2 * 1.293 * (speed * speed * speed) * Area * drag coef.

So, an average car at 50MPH may need 10HP to move the air out the way, but at 100MPH you will need 80HP to move the air out the way. Its all down the the speed-cubed thing. Its also what sets the top speed of a car (unless its limited electronicall)

Stuart.

ps. sorry, im an engineer! i like these sort of things...

 

[MATT'88]

Jesus. Sounds good to me.

Well actually it sounds boring and un-fun as that means i may aswell buy a k1 as in the way fuel goes. I brought the fr diesel because of everyone's review. (And fuel econ) I like the car and yes i maybe a fast driver but still.

Thanks for the heads up and facts.

Matt

 

[darrellr]

I've got a 2.0 TFSi and a typical journey for me is:

• 20 Miles of B-road through Welsh countryside at a 'spritely' pace generally with the odd overtake which requires a modicum of dropped gear/right foot
  
• 90 Miles of Motorway at ~90
  
• 15 miles of dual carriageway / A-road

I get ~31 mpg (NB. I generally fill up on Sainsbury's 97 RON Super Unleaded)

 

[MATT'88]

If i fill up with "PERFORMANCE" diesel will there be any difference?? I could never tell the difference in my petrol cars.

 

[stuartsjg]

If i fill up with "PERFORMANCE" diesel will there be any difference?? I could never tell the difference in my petrol cars.

Hi,

The SEAT training manual says that the centane index of the fuel should be a minimum of 51, which is what everybody sells.

A higher centane index means the fuel detonates at a more optimal point in the compression cycle.

Over 56 there tends not to be a benefit, some say a decrease in performance as the detonation happens during injection which is not so good as it annoys the injectors as the cylinder pressure rises and inhibits injection efficiency.

Again, in the training manual for the petrol engine, it says use RON98 (Octane) for 200HP, but expect a reduction of power with RON95. It doesnt say how much of a reduction.

The petrol engine has knock sensors which tell the ECU what type of fuel is being used and it adjusts the injection and ignition timing to take advantage of this. I think this is common with performance engine. A 1.2l is not likley to have them for cost savings. I think BMW (according to a 325 manual) can take advantage of fuel up to RON112 but i dont think ive ever seen it on sale!

I dont think the SEAT diesels have these sensors so the ECU will inject fuel as everything else dictates.

A preformance fuel may make a diffirence, they may not. Which? says they dont.

Ive not had the car long enough to experiment for myself. I have done 1 tank with millers additive and 1 tank without and only really felt the without was a bit rougher during starting.

Performance is so hard to notice, the only way to test would be to put a car on a Dyno and supply the engine with basic fuel & do a test, then supply with performance fuel & do a test.

The performance should show more HP than the basic. If not, then dont waste your money.

Stuart

 

[RCS2K4]

Lol, you derv owners of Leons don't know just how great the TDI-PD engine is for fuel and performance!

Alongside my MK2 Cupra I drive a 2.2 TDCI Mondeo - And she drinks diesel like it's going out of fashion! I know it weighs quite a bit more, but the 28.6 MPG I get as an average on the motoray's is a little shocking...

 

[CHRI55]

Lol, you derv owners of Leons don't know just how great the TDI-PD engine is for fuel and performance!

Alongside my MK2 Cupra I drive a 2.2 TDCI Mondeo - And she drinks diesel like it's going out of fashion! I know it weighs quite a bit more, but the 28.6 MPG I get as an average on the motoray's is a little shocking...

28.6 MPG??????

Ive never seen my ST TDCI under 30 yet and have a very heavy foot

What you doing in your mondy pulling your cupra along on a trailer all the time. lol

But then your engine is the new 2.2 TDCI type

 

[pacm0n]

I do alot of town driving in the day with short bursts on "A" Roads and Motorways.

My average MPG for my last full tank of Diesel was 39.8. It does seem to be getting slightly better now im getting some miles on the clock.