Improving fuel economy of bigger and smaller vehicles

[Robbie260]

i was saying as much dont worry about the fuel unless you do loads of miles why worry



my car does 40 to the gallon buy a car that does 55 to the gallon 15 more miles but the cast of new car is £7000 how meny years does it cost to make the £7000 back better just keep your old one

Aye doing quite a lot of miles of late and take quite a significant pay cut so anything to help a tank go further.

 

[Wozzaaah]

Always coast in neutral/tickover, when traveling on any downhill

Wrong, the car uses less fuel if you coast downhill in gear than in neutral.

 

[Robbie260]

Driving slower makes a massive difference on a 4x4. Got bored / curious one evening and went through the calculations for power required to move a Defender (basically a brick) through the air. The extra power required from 55mph to 70mph was collosal (for reference it's a quartic relationship).

I've found that in my Range Rovers (big twin turbo 4.4l V8 diesels) that actually accelerating quickly up to speed and then cruising smoothly offers the best economy in a real world scenario. It also means the engine actually gets a bit of a workout which since cruising at 60-70mph it's only doing 1200rpm or so.

Aye seems happiest at 55mph in 5th cruises at that nicely and gets a good millage.

 

[Robbie260]

I found the mild remap on mine gave 15% better economy. 2.0 diesel Skoda Superb. Was 170 bhp, now allegedly 205 and a corresponding increase in torque. 300 quid for the remap. Also went down a tyre size to get more sidewall, mostly for comfort reasons but being narrower they have less rolling resistance. And in a pickup the choice of tyre can make a massive difference. Unless it does actually leave the tarmac stick to a full road pattern. Off road tyres are stupidly inefficient in terms of rolling resistance.
All done out of curiosity really, i.e. how good can I make the old barge. Pretty good is the answer, comfortable and averages 55mpg.

Running brigestone dullers so not the best but not the worst do a bit of off roading so I think sticking with the current tyres is the best option. Had looked at a mild remap but it's up front cost Vs long-term gains there.

 

[Robbie260]

Has it got a DPF?
If not, well then you can get a new, messy, fairly dangerous, time consuming, welding-related hobby and make a biodiesel processor.

Unfortunately 16 plate so dpf is the order of the day, may take it off and clean it though see if that improves things.

 

[willie.macleod]

Aye seems happiest at 55mph in 5th cruises at that nicely and gets a good millage.

Taking it easy up the hills helps as well, dropping down the gears. Headwinds can be a bit of mpg killer as well but not much you can do there.

 

[bricol]

I changed mine from showing me mpg in US units to UK units . . . instant increase to indicated 14mpg

In fact, its a modification I often suggest on American forums when they complain about $3 a gallon . . .

Slightly more seriously - anything with a turbo, as has been suggested, just back off a touch - towing a heavy trailer behind my Lancia integrale on long motorway trips, I would glance down and see the boost gauge reading decent pressure . . . slight lift of the right foot, the boost gauge came back down to the stop and speed remained constant - on the flat anyway.

 

[DAPPH]

i was saying as much dont worry about the fuel unless you do loads of miles why worry



my car does 40 to the gallon buy a car that does 55 to the gallon 15 more miles but the cast of new car is £7000 how meny years does it cost to make the £7000 back better just keep your old one

At current fuel price increases ........... about three weeks ?

 

[Johnnybravo]

Use the wife’s car , run out 90% of her diesel but get it washed before you return it. £10 spent at the Kosovon carwash is a better option than a £60 trip to the pumps

 

[Mr Fro]

Think mith busters did a test on two identical pick ups. Same amount of fuel round a track to see if tail gate down or up used more fuel. can't remember the out come though .

I think the tail gate up truck went slightly further.

My tip is avoid road works! The major arterial route between home and work (26 miles) is down to one lane at 50 mph both ways. It's doubled my commute time and knocked 20% off my mpg from just touching 50 to just under 40.

I've explored all the back roads but they're all chokka with road works too! Oh well, they're only scheduled to last until April...

 

[addjunkie]

Buy a little petrol car, Toyota yaris hybrid springs to mind. Cheap to tax and insure too. But pants for towing or goods carrying

 

[Gareth J]

You could fit an engine preheater, makes a noticeable difference, especially on diesels, especially on shorter journeys. You'll have to buy the preheat fuel (electric or otherwise) though that's normally cheaper than diesel

 

[Bobupndown]

think the tail gate up truck went slightly further.

You'd think the opposite would be the case, tailgate on a pickup would act like air brake? Who knows I'm not a wind tunnel technician.

 

[atomant48]

I had an older XC90 that did just under 30mpg no matter what and I was very careful at measuring and keeping an eye on it (have always done this with all my cars). A work colleague had the same model and assured me he got “about” 40mpg - to be fair I didn’t believe him ! Anyway back in august when it broke down in Scotland and the recovery guy plugged a code reader in he identified (amongst many things :-( ) one of the injectors wasn’t firing. It had always had a slight miss at idle (5 years I owned it…) so my input here is checking its running right - the remap mentioned above might give the opportunity to check a bunch of stuff ?

 

[optima21]

next you'll be telling me to wash and polish my cars

 

[Edward Teach]

Wrong, the car uses less fuel if you coast downhill in gear than in neutral.

Not according to my mpg meter

 

[PhillipM]

Always coast in neutral/tickover, when traveling on any downhill

Why? You'll use more fuel than in gear most of the time.

You'll make more difference to MPG by reading the road/traffic ahead and lifting off well before having to stop for traffic or slow for road conditions, versus steaming up and hitting the anchors, than you ever will with car mods, so if that's not part of your driving toolset, change that first.
I'm not exactly a slow driver but on the road that's my preferred approach most of the time and I tend to get a good 10% more mpg out of others cars than they do if I borrow 'em, used to be a regular thing when I took my grandparents out shopping and they'd grump about me using too much fuel going fast
"I'm using less than you do, your own car says so!"

 

[PhillipM]

Not according to my mpg meter

On what car? Anything remotely modern (I.E, not 30+ years old or on carbs) will cut fuel completely in gear and off throttle.

 

[Greeves246]

Knocking about I use a Honda C125 Super Cub, approx 140mpg and never have trouble parking for free. Even if it is raining always use it for hospital appointments as there is nowhere to park a car after 8.30am and expensive if you do. One of the streets near to the hospital has the highest rate for parking fines in the town.

 

[Edward Teach]

On what car? Anything remotely modern (I.E, not 30+ years old or on carbs) will cut fuel completely in gear and off throttle.

2004 Megane 1.5 Dci