mpg on Volvo 740 Estate 2.0 litre

[tim030654]

My usual overall average on this non-burbo 2 litre redblock petrol engine is 28mpg - with a bit more on long runs.

However, on my most recent Newcastle upon Tyne to Huddersfield 250 mile round trip I decided to (a) keep the speed to 60/65 mph max (+ 30 miles at 50mph through roadworks), (b) keep the revs in region of 2000 - 2800 rpm where possible and (c) use super unleaded fuel rather than ordinary unleaded.

This time I got 35mpg - any thoughts on how much of that is due to a lighter right foot and how much the more expensive fuel?

[stephend]

I'd say it's your right foot!

I tried mine on super unleaded for several months, over enough tankfuls to get a reasonably reliable idea of whether the mpg improved, and it didn't. I typically get 26-28 mpg on mixed motoring, worse around town, but up to 33 mpg on long motorway hauls cruising at the legal limit.

[Prufrock]

Originally Posted by tim030654

My usual overall average on this non-burbo 2 litre redblock petrol engine is 28mpg - with a bit more on long runs.

However, on my most recent Newcastle upon Tyne to Huddersfield 250 mile round trip I decided to (a) keep the speed to 60/65 mph max (+ 30 miles at 50mph through roadworks), (b) keep the revs in region of 2000 - 2800 rpm where possible and (c) use super unleaded fuel rather than ordinary unleaded.

This time I got 35mpg - any thoughts on how much of that is due to a lighter right foot and how much the more expensive fuel?

I do not have official Volvo figures for the 2.0 litres fuel economy but it would be less than the 2.3 (the 2.3 makes more peak torque at a lower rpm so is not working as hard as the 2.0).

745 2.3 Manual - Urban 25.2, 56mph 42.8, 75mph 31.7.

My 1986 745 is an auto but I can get 40mpg on a run driving for economy. I don't think 35mpg is that bad.

Prufrock.

[940SportsEdition]

With out doubt it is your right foot. I too have tried this on two separate runs both to and from the same place, both on days that the weather was more or less the same, and both runs with the right foot on easy mode. The first run was made using the more expensive fuel, and the second the standard fuel, both BP and from the same garage. I got 32 on the first run and 35 on the second. So all right foot, the more expensive fuel is mainly to do with performance rather than economy

[Kevs Estate]

I keep a record of every fill up my car has had and to prove a point mainly to myself that using super was better, i spent a year filling up with regular unleaded at sainsburys. My average for the whole year was just under 27 MPG.
I am nearly at the end of a year of using Texaco super and each week my car has never dropped below 30 MPG and on a couple of occasions, on a long run, i have returned over 40 MPG!
When i do the sums, despite Texaco costing more, with the extra mpg, i have already spent less than a whole year at Sainsburys.
So, to sum it up for me. Supermarket regular unleaded, is like cheap tyres.
A waste of money.

[minesa240x3]

That's the same for me using the dearer fuel makes mine run so smooth but has the legs to get going when desired.
My weekend out got me 27.97MPG so a trip of 262 miles but keeping it at a sat nav speed of 68 at 3000rpm.My car is a 740GLE Estate,Injection,Year 1990 with 2.3L and five speed manual box.Mostly motorway.I'm happy with that.I once towed a car dolly from birmingham and took it at about 56mph and got an awful lot more for my money.Upset a few lorries though.I thought they were restricted to 56mph?Not flipping likely I've overtook them doing 60 plus.
Regards Brian.

[stephend]

Whereas I ran my 740 for something like 6 months on super unleaded, and found no difference at all in performance, mpg or general running, so switched back to standard. Mostly Tesco, in both cases.

Strange how peoples' experiences are so different!

[Prufrock]

Telegraph motoring correspondent recommends V-Power...I am sceptical about the benfits however in an older car.

Only sceptical mind you.

I never buy supermarket fuel - none around here anyway!

Prufrock.

[popuptoaster]

If you put higher octane fuel in a car than it was designed for you will see NO benefit unless the ECU can adapt the timing to suit the better fuel, higher octane fuel allows you to run the timing more advanced and thats what gives you more power (or mpg if you dont use the extra power).

However to do that your car needs to have knock sensors and an ECU that will advance (or retard) the timing depending on the fuel quality, there is no way to get extra power from the fuel without doing that, if your ECU can't do it then it needs to be done manually and then you have to stick to the better fuel.

The fuel companies can add detergents and smooth running aids and that may make a difference to how smooth or clean your engine gets but it wont make you any extra power or MPG without the correct ECU or a manual timing adjustment.

Also in my opinion if your engine does run smoother and cleaner with a newer fuel in it it obviously needed looking at anyway, it should be smooth and clean all the time.

I just went and looked it up,

LH-Jetronic (1982–1998)

Digital fuel injection, introduced for California bound 1982 Volvo 240 models. The 'LH' stands for German: "Luftmasse-Hitzdraht" - the hotwire anemometer technology used to determine the mass of air into the engine. This air mass meter is called HLM2 (Hitzdraht-LuftMassenmesser 2) by Bosch. The LH-Jetronic was mostly used by Scandinavian car manufacturers, and by sports and luxury cars produced in small quantities, such as Porsche 928. The most common variants are LH 2.2, which uses an Intel 8049 (MCS-48) microcontroller, and usually a 4 kB programme memory, and LH 2.4, which uses a Siemens 80535 microcontroller (a variant of Intel's 8051/MCS-51 architecture) and 32 kB programme memory based on the 27C256 chip. LH-Jetronic 2.4 has adaptive lambda control, and support for a variety of advanced features; incincluding fuel enrichment based on exhaust gas temperature (ex. Volvo B204GT/B204FT engines). Some later (post-1995) versions contain hardware support for first generation diagnostics according to ISO 9141 (a.k.a. OBD-II) and immobiliser functions. The 1995 and newer Volvo 940 vehicles are one such example.

If I understand it right it looks like if you have LH Jetronic 2.4 or later the ECU CAN adjust the timing for better fuel, by how much I don't know and best confirm with an expert.