Long Drive - unexpected fuel economy!

[henry_exeter]

Well, I finally made the trip from Exeter to Faversham in Kent to have my new hood fitted today (many thanks to the excellent job done by SE trimmings - as advertised in the Stag Mag). The journey there and back today was 440 miles. I filled the car along the A303 (just after Stone Henge) - the tank was completely full (petrol level to the top) - I then used GPS to measure mileage. When I filled again upon returning home 360miles later, I calculated I had averaged 28 miles per gallon.

It's a standard Stag V8 (rebuilt by HRS around 20k miles ago) with the only mod being a BMW diff and 185x80R14 tyres (I believe they are slightly larger than the standard tyres). The speedo therefore underestimates by around 8%. Driving style - a mix of motorway use and A Roads - and I didn't drive at a constant 50-60MPH!

I had always been led to believe the best I could expect was around 21MPG - so has the BMW diff made such a big difference or am I just lucky?!

Pics of the new soft top and 'new' hard top (just finished having it repainted) will be posted soon.

Henry

[redstag]

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I have achieved 28mpg on longruns such as Bedfordshire to Cornwall several timeson the occasions when I have checked the fuel consumption. Everything standard (I think 185/80/14 is the standard size tyre).

Mines a manual o/d, what's yours?

Pete

[DJT]

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Good news, Henry. I look forward to seeing it very soon. If you pop round next week, bring some overalls as I will be lifting about 200 paving slabs :shock::shock:

Your tyres are the standard size for the original wheels. The handbook states 185/70HR14 as an option, but I have been told by people in the industry at the time that these were never fitted. Later Stags came out with 175HR 14 (again, full 80-profile.)

If your speedo is 8% under-reading, I guess you have a higher ratio diff. The often used 3.45:1 Triumph diff will give approx 7% under-read, which is what I have on mine and the under-read is confirmed by TomTom.

Dave

[henry_exeter]

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Hi

It's a manual O/D.

Out of interest, whilst driving back at around 70mph, the overdrive dropped out a couple of times. To re-engage it all I had to do was switch it out and back in again or wait - it reengaged itself afetr a few seconds. Any ideas? I guessed a funny solonoid of loose wiring - but also considered low oil (it was last topped up around 1000 miles ago). It isn't a major issue.

Henry

PS Dave - I'm on island in Poole Harbour next week eating worms and trying to survive- a group of us are raising money for Anthony Nolan Trust. So sorry, I won't be able to help lift the paving slabs..!!I will however call round when I get back to show off my recently repainted hard top (thanks Stagster) and new hood.

[DJT]

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henry_exeter wrote:

PS Dave - I'm on island in Poole Harbour next week eating worms and trying to survive- a group of us are raising money for Anthony Nolan Trust. So sorry, I won't be able to help lift the paving slabs..!!

Let me weigh this up. Lifting paving slabs vs. eating worms? I think I'll stick with the slabs. Have fun.

Dave

[henry_exeter]

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I'm told they are high in protein...!



Henry

[alan_thomas]

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henry_exeter wrote:

I'm told they are high in protein...!



Henry

Henry if you get tired of worms I believe there are red squirrels on Brownsea island - much tastier than the common grey ones!

- Alan

[chopperman]

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Hi,

I have just filled up after my run from Kent to Goodwood and return and calculated 28.99 mpg.I have a standard diff. and wheels but a 4 speed auto.

With my other Stag (now a non runner) with a 3 speed BW35 the best I ever got was 22mpg.

Keith

[GDPR]

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As I use my car as a daily chariot, I reckon I'm saving £15 a week on fuel (or putting in £15 less) since I had the ZF fitted - on that basis it will have paid for itself in two and a half years, not withstanding the engine wear saved....

I know for the sort of mileages some of you do, it couldn't be justified on cost alone...

Russ:dude:

[mickl]

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henry_exeter wrote:

Hi

It's a manual O/D.

Out of interest, whilst driving back at around 70mph, the overdrive dropped out a couple of times. To re-engage it all I had to do was switch it out and back in again or wait - it reengaged itself afetr a few seconds. Any ideas? I guessed a funny solonoid of loose wiring - but also considered low oil (it was last topped up around 1000 miles ago). It isn't a major issue.

Henry

PS Dave - I'm on island in Poole Harbour next week eating worms and trying to survive- a group of us are raising money for Anthony Nolan Trust. So sorry, I won't be able to help lift the paving slabs..!!I will however call round when I get back to show off my recently repainted hard top (thanks Stagster) and new hood.

Hi Henry



I had this problem untilrecently when car was in for service, the garage replaced broken wiring under car at gearbox, I had already replace the section of cable that runs from switch to console to no avail.



I found it a bit annoying to have the overdrive hunting at 70+mph



Hope this helps



Mick L

[henry_exeter]

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Great - just the reply I was hoping for! Wiring is my speciality - stripping down overdrives isn't! I'll redo it when I get back next week. As you say - dropping in/out unexpectedly of O/D at 70MPH is a little exciting!

Henry

[dogsnadgers]

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I did two round trips of 65 miles round trip last weekend and reckon I got over 25mpg, I did 32.5miles, thenthe car sat for several hours and I returned home so I was quite impressed with that. By contrast I have a new Ford Mondeo 2.3 duratec auto and the trip computer says I am getting 27.0 average mpg and that has been cruising at 70-75mph on the motorways so it makes the Stag look good (and more fun!).

[henry_exeter]

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The impression I am starting to get with my Stag is that on long fast runs the fuel economy I get is comparable to my newer, less fun and more bland car.

On shorter trips in to Exeter when I spend a lot time sitting going nowhere fast the economy falls off.

The moral? Do lots of nice LONG trips in the Stag.

Henry

[Guest]

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My stag does about 20mpg around town, the wifes focus ST does 23!:shock::shock:Took her focus to nottingham at 70mph on the motorway, 31MPG!:shockretty crap eh?

Jason