Lousy Diesel MPG (not a BX) DW10 Donkey

MULLEY · Post by **MULLEY** » Sat Mar 31, 2007 6:56 pm

Can never underestimate drag, if you took the wing mirrors off the car & filled in all the shut lines in the bodywork, the car would be a truckload more economical (not that practicle though) & because it would be more slippery would conversly be quieter as well....

jeremy · Post by **jeremy** » Sun Apr 01, 2007 7:32 am

To get good drag there needs to be great attention to detail. I had a Renault 21 which had a drag co-efficient of 0.30 (BX 0.34. Sierra 0.33, Scirrocco 0.37) and what was noticeable was that the glass was virtually flush, the spoilers were right both ends (back one came down to prevent suck etc), door handles were nearly flush, careful front design with no incorrect flat surfaces and so it went on.

It was noticeable when driving as well - no wind noise and the thing had a very good high speed performance and seemed quite effortless at speed. Lift off and it seemed as though it would run for ever.

M · Post by M » Wed Apr 11, 2007 4:44 pm

Holiday run - all A & B roads, never over 65MPH, no roof box, car loaded to gunwhales with children, stuff, mother in law, wife etc etc - 510 miles - averaged 47 MPG.
Much better.

Moral of the story - no roof box and keep it under 70!

Oscar · Post by **Oscar** » Wed Apr 11, 2007 4:54 pm

If I keep the BX to 70, I'll get an extra 50 miles out of a tank.

It's bloody difficult though, especially when taking on some chav/BMW/random idiot....

cavmad · Post by **cavmad** » Wed Apr 11, 2007 4:56 pm

My TZD is still doing reasonably well on fuel despite constant thrashing everytime I`m out in it. Haven`t measured it exactly but would think mid thirties at worse with the 1.9TD engine.

DavidRutherford · Post by **DavidRutherford** » Wed Apr 11, 2007 5:52 pm

A while back a friend of mine had a Pug 405 TD estate.. with roof bars. He used to complain bitterly that he didn't get the same fuel consumption as I got out of mine.

"well then, take your roof bars off, they're costing you a fortune"

"but they're usefull"

"you've used them once in 2 years."

Eventually I gave up trying to persuade him to take them of... and just took them off myself.

Released something like 6-7mpg, and the car was quieter. We worked out that over the mileage he'd had them on for, he'd wasted something like £220 of fuel.

MULLEY · Post by **MULLEY** » Wed Apr 11, 2007 6:31 pm

I can believe those costs, most people are driving around totally unawares.....':oops:'

Bxaholic · Post by **Bxaholic** » Wed Apr 11, 2007 11:42 pm

I've a 1.9d Berlingo kept here which I use now and again and I find the difference in fuel consumption compared to my TZD estate amazing, cant work out why as the Bling is only 3 years old, whether they're heavier in weight or something I dont know.

jeremy · Post by **jeremy** » Thu Apr 12, 2007 12:06 am

Its partly aerodynamics - same power will propel a BX or ZX 1.9D at 103 MPH will propel a Berlingo at 88!

classic2cv · Post by **classic2cv** » Thu Apr 12, 2007 2:10 am

our bling has a top speed of just 99 mph (Citroen’s figures)

it is partly down to the aerodynamics and it's heavier (all the modern safety stuff )

but the very high gearing is to blame as it will never get to max revs in top gear

when were driving in a 30 mph zone and the road is flat we can leave it in 5th and not touch any of the pedals as it will do 30 at idle

if we want accelerate quickly we have change down to 3rd

the Bx will pull away from 30 to top speed with ease

stuart_hedges · Post by **stuart_hedges** » Thu Apr 12, 2007 9:44 am

I once drove a GS over the Alps with a roof box on.

[voice=Orville]I wish I could fly![/voice]