On Sunday 31st October I drove from St Gervais [ on the side of Mont Blanc] to Calais.

 

The journey was 549 miles and including stops the journey took 8 hours 21 minutes. Most of the journey was on motorways and we were cruising at 80 mph [just below the max of 130 kph.

 

Amazingly, we averaged 65 mph and 56.4 mpg for the day according to the trip computer [confirmed by filling the tank at Calais], the car was fully loaded with four adults and their luggage.

 

I was impressed to say the least    .

 

 

Very good........

 

Not that we've been for 18 months but our vehicles always seem to do better mpg whilst on our visits to Italy than what I get in the UK...........

Diesel engine, presumably?

 

Yes 150 bhp diesel. 

9 hours ago, Berisford said:

Very good........

 

Not that we've been for 18 months but our vehicles always seem to do better mpg whilst on our visits to Italy than what I get in the UK...........

I had the same experience taking a BMW 320d to St. Tropez area a few years ago.

Around here the best  I got on a long trip was about 53mpg on the French run it was just over 60.

 

My theory is that the much smoother French roads give less rolling resistance than our rougher stone-rich asphalt in UK.

It was confirmed by the much quieter ride on the dreaded run-flats than we get at home.

 

It must take some energy to turn fuel into road noise, hence the better MPG.

Much less traffic on the Autoroutes with the exception of the mad exodus for les vacances, you can maintain a cruising speed mile after mile without being slowed up or having to accelerate to avoid being boxed, in 15 years I have only come to a stop in a tailback twice.

 

549 miles nearly all on Autoroutes and I'm guessing without any holdups, in my part of the UK you would be lucky to get 10 miles like that.

 

The above does not include Paris & le périphérique.

^ Yep. Newton's first law says "If you can keep the speed constant you'll use much less diesel, weight loading almost irrelevant; it's only the aero drag and mechanical frictional losses you have to overcome" (paraphrasing into context).

I've driven to the South of France, scores of times in the past, and was convinced the standard diesel in France was better than the standard diesel in UK.

Not sure it has any difference in cetane rating but never actually checked!

 

 

It certainly has or had more defoamer, I used to have a hell of a problem refilling the Octavia 1 and 2 with diesel in the UK, no problem at all in France, the Yeti has the problem licked so I don't know if the UK fuel remains as was or has now been improved.

 

You could be right regarding the calorific value, I always get less to the gallon in the UK but put it down to the journey profiles and traffic, since covid all my journeys aside from country to country have been local, last time in the UK my fuel economy did not drop, because of the fuel shortage I had refilled at Calais and drove for the 2 or 3 weeks in the UK on the same fuel, usually within a week I will have filled with UK fuel.

 

And now I come to think of it the journeys France to England (190 miles) vs the exact same return trip are always more economical and yet there is only 9 meters of elevation difference between the two properties, the fuel for each trip 99% of the time has been bought from the destination country.

 

Elevation does make a difference, I frequently travel 25 miles to Arras which is 40m lower than my property, there is an 6mpg difference between the outward and return journeys on the same roads at the same speeds, the mean of the two equates to my average for similar journeys.

 

Returning to sea level from the Alpes would give better economy than in the other direction although the difference would be minimised by the long journey, add in different fuel and it could be significant.

We have travelled extensively around France for our summer camping holidays with the children, in a variety of diesel cars, a Laguna 2.2 d, and a BX 1.9 rd and our recently traded in xc70 d5.

I always thought they all did better milage and did appear to run much better even on the back roads, I assumed it was the warmer dryer weather, also remember as mentioned it was allways easy to cruise along with out hardly any disruption  excepting the toll booths stopps to pay on the almost glass smooth toll roads, also found the autobahn roads in Germany to be super smooth comared to our poor excuse for m ways never mind a/b ones.

I did a 250km trip in my IV yesterday, and travelling at 130kmh on the autoroute, I averaged 52.31mpg for the journey. Some of this was spent in traffic jams, as we hit Toulouse at peak time on a Friday evening.

I am quite pleased to get so close to a diesel, especially considering I was driving in possibly worse conditions, although admittedly it was not all motorway. I still need to do a long motorway trip to see how well the car performs.

Edited 6 November, 20214 yr by CageyH

On 05/11/2021 at 08:46, J.R. said:

It certainly has or had more defoamer, I used to have a hell of a problem refilling the Octavia 1 and 2 with diesel in the UK, no problem at all in France, the Yeti has the problem licked so I don't know if the UK fuel remains as was or has now been improved.

 

You could be right regarding the calorific value, I always get less to the gallon in the UK but put it down to the journey profiles and traffic, since covid all my journeys aside from country to country have been local, last time in the UK my fuel economy did not drop, because of the fuel shortage I had refilled at Calais and drove for the 2 or 3 weeks in the UK on the same fuel, usually within a week I will have filled with UK fuel.

 

And now I come to think of it the journeys France to England (190 miles) vs the exact same return trip are always more economical and yet there is only 9 meters of elevation difference between the two properties, the fuel for each trip 99% of the time has been bought from the destination country.

 

Elevation does make a difference, I frequently travel 25 miles to Arras which is 40m lower than my property, there is an 6mpg difference between the outward and return journeys on the same roads at the same speeds, the mean of the two equates to my average for similar journeys.

 

Returning to sea level from the Alpes would give better economy than in the other direction although the difference would be minimised by the long journey, add in different fuel and it could be significant.

We did 375 miles from Reims to Mont Blanc and the mpg was 57.6, although we took it steady and the car only had two people on board

^ ^ ^ ^ yeah but it is downhill from the alps to calais  :-()