Fuel economy - Max miles to a tank?

Okay just had a google on the subject.

Interesting read, curious to your thoughts on this...


http://www.popularmechanics.com/cars/hybrid-electric/a5977/coasting-in-neutral-fuel-economy/

It's gallons per hour that he uses as his measurement. Not miles per gallon. Yes, he also mentions certain trip computers measure air flow and not fuel flow, so those trip computer gains I mentioned could be seen as invalid. We don't, I certainly don't, know what Renault use as the data inputs for their trip computers.

Where does the Popular Mechanics guy cover the amount of fuel used in relation to distance travelled? Or are we to presume gallons per hour equate to a uniform distance travelled per hour? An engine under load (say going up hill) uses more fuel, gallons per hour, than one not under load (say going down hill).

Perhaps me saving fuel when coasting was historically true due to learning to drive in cars with carburettors, and fuel injection systems have now made cars at idle highly inefficient, yet highly efficient when not under power; engineering advances also having eliminated the engine and gearbox drag that used to bring you to a halt.

I would still expect to travel a greater distance in neutral down hill than in gear and subject to engine and gearbox drag. If modern cars at idle are highly inefficient compared to remaining in gear I'm happy to accept that. Although they must be hugely inefficient at idle to burn more fuel when travelling two miles down hill in neutral, compared to attempting to cover the same two miles in gear with no fuel being used, but having to use fuel at some point to cover the remaining distance when momentum runs out.
 
Gosh you boys must drive like grannies! My regular fuel consumption is about 250 miles a tank. I cannot drive my Clio slowly it just begs me to drive it enthusiastically!
 
Well that sounds horrifically dangerous.

When you're 17, would rather save money for beer than petrol, and have a sorted 1275 Mini it felt like it was fun. Not something I'd do now or encourage. Growing up on the Welsh Shropshire border one has a tendency to do foolish things in cars. Thankfully I never had an accident that involved anything bar a hedge, and that was due to running out of talent and meeting a lot of mud outside a farmyard. Massive understeer and a 10mph impact after a 90 left. Lesson learnt.
 
So how on earth do you get 400 miles from a tank? Just long slow motorway journeys?

Pretty much. Although driving like grandma on A roads probably still yields good mpg, but not as good as constant motorway cruising at 55-60mph. The minute you drive them properly the efficiency plummets and mpg is dreadful. Having a Cup spoiler will add drag too, so a car with a GT spoiler or no spoiler probably returns slightly better mpg. Not that anyone is likely to be able to notice. Also a clean smooth car will have a better coefficient as it goes through the air, not that you'd notice it in mpg either.
 
Dang it, don't think I'd have put my cup spoiler on the 197 if I knew it reduced my mpg!!!:tongueout:anic:
 
Well that sounds horrifically dangerous.

Agreed. 5th down a hill will keep you around 70mph and if you see your mph going down, just whack it in 6th. No fuel consumption for seven miles and no brake pad usage either.

ShantiT, you must go through a **** load of brake pads driving like that.
 
ShantiT, you must go through a **** load of brake pads driving like that.

Honestly, I never noticed. As I previously mentioned I was a teenager in a feather weight Mini. I don't coast down seven mile hills as an 'adult'. No point and no need to. It may have used up a little more friction material, but probably a negligible amount.
 
Dang it, don't think I'd have put my cup spoiler on the 197 if I knew it reduced my mpg!!!:tongueout:anic:

Yea, gutting eh. Think of all the money you could have saved to spend on penny sweets. I just think they look too garish, but that's personal taste.

As a purely cosmetic addition that has zero effect, other than creating drag, I'd rather mine wasn't fitted, but the rest of the spec was too perfect to walk away from. Could aways take it off easily enough. The idiots at the import centre didn't fit the sticker to protect it from rubbing against the aerial when the boot opens either. Thankfully there are no marks on the paint, but I think the boot has only been opened about ten times in the cars life.
 
Honestly, I never noticed. As I previously mentioned I was a teenager in a feather weight Mini. I don't coast down seven mile hills as an 'adult'. No point and no need to. It may have used up a little more friction material, but probably a negligible amount.

Ah sorry, read your reply wrong, I thought you've been doing it in the 197/200! Lmao.
 
theres a few modern motors that now "coast" when on nthe over-run - think Porsche does it with the pdk gearbox and also trucks have a coast function
in conjuction with the gps to coast down hills - its the latest fuel saving fad!