Shell vs Super market petrol !!

[Old Hack]

If you mostly drive motorway miles, it is actually more efficient to get cars with a bigger engine (V6 or V8). My 6lt VXR8 does 2.2k rpm in 6th gear when doing 80mph. It consumes the same fuel as my 2.3T Mazda 6 MPS, which is doing 3.5k RPM in 6th gear at 80 mph, which means the turbo is dishing out boost, which is turn means increased fuel consumption. If it's urban driving, I would drive the MPS, but end up using the VXR8 to race the chavs. Oh the fun!

Isn't that some kind of oxymoron

I have just had the GL chipped and it now has over 470ft lb, which really does surprise people when you give it the beans.

MPS is a car I keep thinking of buying - Q car extraordinaire!

[BolshieBastard]

Does it? I recently saw a report on TV which showed a Prius and an M3 doing 10 laps of a track at the same time with the Prius in front. At the end of the test the M3 had used less fuel! Basically it comes down to how you drive a lot of the time.

More like the final gearing.

When my wife drives her car, she always changes gear at about 1200 rpm. She even has the thing in 5th (top) gear at 30mph doing just over 1250rpm. She gets less mpg then when I drive it turning about 2000rpm in 4th.

I constantly ask her why is she running in such a high gear when the engine is barely doing more than idling speed? Driving it economically, she says

Petrol engines generally deliver best torque and economy around 5400rpm although each manufacturer may have set the engine up differently.

A heavy right foot and wrong gear selection will impact mpg far more than the use of branded v supermarket fuel ever will. People who use premium branded fuel nearly always claim vastly improved mpg as do people who use tuning boxes (strange that manufacturers dont set their cars up for the particular markets to deliver these improved performance attributes!).

[original PM]

indeed on the subject of tuning - what are the problems with chipping the engine to give both extra power and increased MPG - and more to the point why was the engine not set up that way in the first place?

just asking cos I am thinking of doing it (mainly for the MPG increase rather than the power)

[EternalOptimist]

A swedish study once showed the best way to drive, in order to be fuel efficient, was to accelerate to your speed as fast as you can, then stay at that speed as long as you can, with minimal changes to acceleration, and deceleration. If you try and do this, you become a better driver, for you look out for traffic lights more, and notice queues so you end up planning a journey better, i.e. you look ahead and slow slightly, trying to ensure you don't have to come to a proper stop.

Interesting. I drove up to Oban from Manchester a few weeks ago, and I was complaining to the missus that my cruise control was busted. Half way up the m74 she got the manual out and told me to touch the brakes. The cruise control came on.
Apparently it wont switch on until it has confirmed that your brakes are working

[Paddy]

Interesting. I drove up to Oban from Manchester a few weeks ago, and I was complaining to the missus that my cruise control was busted. Half way up the m74 she got the manual out and told me to touch the brakes. The cruise control came on.
Apparently it wont switch on until it has confirmed that your brakes are working

I think my cruise control is faulty. I turned around to get some sandwiches and the car wondered over the motorway.

[bluetoaster]

indeed on the subject of tuning - what are the problems with chipping the engine to give both extra power and increased MPG - and more to the point why was the engine not set up that way in the first place?

just asking cos I am thinking of doing it (mainly for the MPG increase rather than the power)

I did it with a 1.9tdi VW unit. It made the car far more driveable and I was no longer thrashing it everywhere just get going. It made no difference to the mpg for me. As for the changes to the car I would strongly recommend it, though I doubt I'll do it again as it really upset my insurance company.

I just make sure I get the right engine now when I buy a car.

[Old Hack]

indeed on the subject of tuning - what are the problems with chipping the engine to give both extra power and increased MPG - and more to the point why was the engine not set up that way in the first place?

just asking cos I am thinking of doing it (mainly for the MPG increase rather than the power)

Re-mapping is ok, but the piggy back units aren't that good.

Effectively, the manufacturers will create a map for all countries, e.g. from Albania, to Nigeria, they will have the same map (not in all cases, but most). Due to this, the map they put with the car, is dumbed down to the lowest common denominator, which is the lowest grade of fuel. What re-mapping does, is make sure that the engine is optimised for Western European fuel, which allows for a better 'burn' in the cylinder. This means more power, bhp and torque, and the by product of more power, is that you use less fuel.

You can now get maps for economy, which is a more specialised map, but you can see 15%, and if you are doing large miles, it makes sense.

I just like the extra power myself.

[AtW]

Petrol engines generally deliver best torque and economy around 5400rpm

Fuel duty+VAT tax cheat!!!

[BolshieBastard]

indeed on the subject of tuning - what are the problems with chipping the engine to give both extra power and increased MPG - and more to the point why was the engine not set up that way in the first place?

just asking cos I am thinking of doing it (mainly for the MPG increase rather than the power)

Despite what people say, you dont get the benefit of both at the same time. In other words, its an either or situation.

People seem to think manufacturers tune their cars for the worst case scenario ie tulip 3rd world fuel, low atmospheric pressure etc. They dont. They tune the cars for the intended market. Do people seriously think manufacturers are not tuning their cars for the european market to take account of

best fuel economy
higher RON of european fuels
strict european emission standards
general european atmospheric pressure
best performance within the envelope

A tuning box can change these parameters but does not give the improvements many claim of better mpg and better performance.

999 motorists out of 1000 wouldnt and couldnt do a controlled test on performance \ mpg before tuning box fitment and after.

[Old Hack]

Despite what people say, you dont get the benefit of both at the same time. In other words, its an either or situation.

People seem to think manufacturers tune their cars for the worst case scenario ie tulip 3rd world fuel, low atmospheric pressure etc. They dont. They tune the cars for the intended market. Do people seriously think manufacturers are not tuning their cars for the european market to take account of

best fuel economy
higher RON of european fuels
strict european emission standards
general european atmospheric pressure
best performance within the envelope

A tuning box can change these parameters but does not give the improvements many claim of better mpg and better performance.

999 motorists out of 1000 wouldn't and couldn't do a controlled test on performance \ mpg before tuning box fitment and after.

I disagree completely. Petrol will be between 92-102 throughout Europe. In the UK its 95-101. You cannot tune for 92, and have a benefit for 101, and vice versa.

Diesel, as well, is of varying quality even through Western Europe. Given we can now drive to and from eastern Europe, manufacturers have to take into account the lower quality of fuel there, so are legally bound to make sure they tune to the lowest common denominator. No manufacturer has a map for UK, one for France, one for, etc, etc, etc.

I believe the 999/1000 comment is incorrect too. especially on the bhp. On a N?A car this might be true, but on a TDI, or TSI engine, the gains are significant, in excess of 25% most of the time, especially at the bottom end, so it's obviously different.