Real petrol consumption V google map estimate

Regardless of the car MPG changes depending on how it is driven - and the traffic conditions encountered. If you get stuck in a traffic jam with the engine running you're doing 0 MPG. So all they can do is give some sort of average figure - probably based on official MPG figures for a model, which are notoriously inaccurate for real world driving.

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Well Dave you've certainly narrowed it down.

Similarly, if you are doing the journey late at night when there's little traffic around, you can do a constant 70 mph. On the other hand, if there is a lot of traffic doing about 70 mph but with some slower lorries in Lane 1, and with Lane 2 and 3 composed mainly of traffic doing 80-90, then you cannot maintain a constant speed, even if your average works out about the same; instead there will be times when you get stuck behind a lorry if there is too much traffic at that moment for you to pull out while maintaining 70, and you may then have to accelerate briefly to 80 to match the speed of the traffic that you are joining until you can pull back in again. The latter, with periods of acceleration, will tend to use more fuel.

I know this well: on a 200-mile journey from Oxfordshire to North Yorkshire during the day, my fuel consumption for the journey was about 55 mpg (consistently) whereas the return journey in the late evening on a Sunday night, with much lighter traffic, averaged around 62 mpg. I'm assuming that there wasn't *always* a prevailing wind from the north, opposing me on the way north and assisting me on the way south :-)

(If I don't say it, someone else will!)

When you were heading to N Yorks, you were going uphill...

Chris

I used to drive to Aberdeen quite a bit and always got better MPG coming back to London. ;-)

On a very long journey like that my MPG figures were remarkably constant between journeys (in the same car). I'd guess the shorter the journey the more chance of a variation.

I remember seeing "up to" 68mpg for the Focus 1L Ecoboost; the real figures I'm getting are 37 to 40mpg.

But I am enjoying the performance, I must stop drag-racing away from traffic signals. ;-)

My last two cars, a Peugeot 306 HDi (2 litre) and a Peugeot 308 HDi (1.6 litre), both give much worse figures than the manufacturers' figures. I averaged about 50 mpg for the 306 and got about 54 mpg so far for the 308. The 308 with (I think) the same engine and gearbox, got something like 120 mpg for a notorious test run around the UK under conditions that were not specified (and so may have been much slower than normal traffic and at night when they could maintain a constant speed) and fell foul of the advertising standards people.

I'm surprised how much variation in fuel consumption I get even with roughly the same mix of driving (a bit of motorway and dual carriageway, a small amount around town and mostly country lanes with some hills). I measure by brim-filling to the third cut-off point of the diesel pump after letting the fuel level get towards empty (ie I usually put in about 50 litres), and I usually use the same filling station (if not precisely the same pump!), though that's only because it happens to be the cheapest garage round here. Figures fluctuate over the range 45 - 60 mpg, with most being around 56 - very roughly a Normal distribution.

Yes that does tend to undo all attempts to be thrifty with fuel!

I'd expect more like 45mpg from a 1.6 Corolla as ex-OH used to get that from her 1.6 Escort on a run. Similarly my L-reg 325i auto would return

I'm

Going North is all up-hill.

I calculate mpg in exactly the same way as you do, I have an ongoing spreadsheet and I only trust mpg figures which are calculated in this way. The rest is propaganda. :-)

But it's always a relief to get away from the Southeast as it sinks slowly into the sea.

More like £15 - £18 in *fuel* for an average sized petrol-engined car, I'd say.

You can make the cost look more by calculating a mileage rate which includes depreciation, a proportion of servicing and repair costs and a slice of the replacement parts bill.

Either way is right.

You could make an interesting comparison with the train journey. I recently paid £32 for about a 100 miles train journey. So much the same, really, even considering that most of the car cost goes on fuel taxes. I always wondered about the bulk weight per passenger involved with the rolling stock, how can this be efficient? On the other hand, many trains are electrified nowadays. With trains, you are tied to finding a stations and timetables, on the other hand you have the freedom of not bothering finding parking spaces. But trains are really only suitable for a regular travelling pattern; any variation is quite hard to accomodate; in a car you just type in the sat-nav. In the above journey, the train was actually quicker, but that was station to station only.

johannes wrote: [snip]

It's interesting to try comparing the real costs of bus versus train travel.

For a full bus, say 40 passengers; the costs are: one driver, a proportion of the ticket selling overhead, the bus itself, fuel, and road taxes.

For a full train (maybe 1000 passengers) my guess is that:

2) some of the other costs (a proportion of the ticket selling overhead, the train itself, fuel) is - per passenger-mile - much the same;

In reality most long bus journeys cost as little as a tenth of the comparable train journey - so I'm very surprised at this difference.

My question is therefore: "Why is train travel so much more expensive than these crude calculations would suggest?"

I've not been able to find credible answers to this on the web - most calculations appear to be done from a preconceived political view that rail costs are vey high and that no government in its right mind would ever put money into a railway system.

I have heard the same about air travel; that when you exclude government-funding of military aircraft there isn't sufficient commercial justification for any sort of air travel industry.

A new locomotive is perhaps 5 million UKP, then you have the cost of the carriages.

A luxury coach is about a quarter of a million; a double-decker bus perhaps half of that.

Chris

The new Google maps doesn't, possibly because it isn't very accurate.

If it lowers the rolling resistance or air resistance.

So a roughly similar cost per pssenger, then ...

I should think the rail loco and coaches have longer life (in mileage) than the bus ...