Morris Minor Owners Club

There's been quite a bit of discussion on here about what sort of fuel consumption one can expect from a Minor, with figures anywhere between 30 and 45mpg being given. Therefore as a fairly high-mileage driver I decided to start keeping a fuel log to work out what fuel economy I'm getting over a long period. I've now done 3000 miles since starting the log, and can report my results....

The car is a standard late 1098cc 4-door saloon, running original wheels with radial tyres. The engine is in fair condition, with good compression of ~160psi all round when I last checked quite a while ago. Regularly serviced by myself and always a good reliable runner. On the downside the timing chain rattles a bit, the crankshaft is a little bit noisy and oil consumption seems to be increasing. The carb is a standard HS2 and was rebuilt partway through the period covered by the log. I tend to run the car slightly on the lean side of normal so as to get the best economy, and have cheap ASDA 20w/50 in the carb dashpot. Fuel is standard unleaded, mainly from my local independent garage (with a few exceptions), and always filled right to the brim.

My driving style is fairly normal (I'd like to think), but I tend to avoid excessive revs unless I need to accelerate particularly quickly. Cruising is normally at an indicated 60mph, occasionally 65 or 70. Basically I don't thrash the car, but am not trying for very best economy either. Most of my driving is on A-roads, with a bit of town driving and light traffic whilst commuting to work too.

As part of the exercise I've also tried to work out how accurate the odometer is, given that if that's exaggerating distances driven it'll inflate the MPG figure. I've done this by comparing the distance reported by the odometer with that on google maps for a known route. It doesn't give a consistent error but it's in the range of 3.5 to 5.5%, so I'm assuming a figure of about 4.5% fast.

Here's the figures:

I found that quite interesting 46 mpg was good

Very interesting.
Replacing the timing chain should give more accurate valve and ignition timing, hence a more efficient engine.
Not sure how accurate Google maps measurements are, I'd use a GPS to check the accuracy of the speedo.

Not bad going! I used to keep a similar log, until i added up the fuel costs...

Well done keeping that Log - keep at it! And well done also correcting for the over reading odometer - it may still not be deadly accurate - but it can't be too far away now - although a GPS check would be interesting. I wish I could get that sort of mpg from my Traveller.......

Just stop wearing diving boots, and remove all the cast iron spares you carry, simples!

I have tried comparing the odometer (and the speedo) against my GPS. Strangely, the errors don't seem to match up. If the GPS is to be believed, the speedo seems to fairly consistently over-read by about 11%. However, the error rate of the odometer measured against distances reported by the GPS is variously between zero and about 6%. To be honest, I'm not sure what to believe, but I think it's fairly safe to say that the odometer is over-reading by at least a couple of percent.

It was indeed pretty scary adding up the cost of all the fuel .

The odometer is gear driven - so it doesn't change with age. Likely the variations you see are just down to difference between the actual distance travelled and the GPS measuring 'points' and joining them up - or wheel spin ?? The spring in the speedo dial is likely to have weakened with age - and possibly the magnetic coupling may also have weakened over the years - so that may explain the v optimistic speeds !

6 to 11% over reading is fine, even my 2007 car over reads, if the speedo under read, the manufacturer would be in trouble.

There is almost nothing we can do about the price of petrol, it may be scary but we all have to suck it up or quit motoring, which is scariest?

Or change to LPG which is almost 50% cheaper than petrol........ The moderns I have had recently all had/have speedos that read a constant 3 mph high right up the scale.