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This is my first post since introducing myself in about June 2010. I was then driving a Seat Leon FR TFSI DSG (2.0l TFSI petrol with flappy paddles - very sporty!), which was a lot of fun but was absolutely killing me in fuel bills. I drive roughly 30k miles per year and £400/mth on fuel was just too painful, especially as I was getting into efficient driving and trying to eek out as much as possible per litre. ;)

So I bought myself a brand new tree-hugging version of the same car: the Seat Leon Ecomotive SE (1.6l CR TDI manual 5spd 'eco' tall gearing etc). I absolutely love the car but I feel I'm not managing to get the mpg figures that I should be and I'm hoping you guys will be able to steer me in the right direction.

I'm currently getting an honest/calculated mpg of 60.5 UK mpg (50.4 US mpg) with my Ecomotive. The official combined UK mpg figure for this car is 74.3 UK mpg.

Compare this with me (eventually) getting an honest figure of 37 UK mpg (30.8 US mpg) from my previous boy racer car, which had an official 'combined' figure of 35.8 UK mpg.

Both cars have 55l tanks and I've gone from roughly 400miles maximum with the FR to roughly 800miles max with the Ecomotive, so it's *way* more efficient, but I'm keen to improve even further if I can as I'm not meeting the official figures yet.

If anything, I'm trying to drive much more efficiently with my Ecomotive than the FR but I'm not getting anywhere near the official figures, which I managed to exceed with the FR after lots of practice and patience.

The things I'm trying to do include:
- very gentle acceleration
- avoiding braking (or accelerating) unless I have to
- keeping the throttle as constant as possible and letting the speed vary up/down hills instead
- not using cruise control
- taking the 'racing line' on corners etc to reduce loss of speed
- coasting in gear and changing down as late as possible
- keeping the revs below 1,500rpm to try to avoid boost

I think I remember reading that brief hard acceleration in lower gears until you get up to speed is actually more efficient than slow acceleration, for diesel cars, but it seems counter intuitive. Any advice on that point?

Any advice you could give on other things to try, or where I'm going wrong above would be much appreciated! Most hypermiling advice I've found seems to be focused towards petrols and I'm sure there must be diesel-specific knowledge that I need to tap... :)

Let me beat msirach to this one and point you to The CleanMPG primer (http://www.cleanmpg.com/forums/showthread.php?t=19408) which has lots of useful links.

You didn't mention it but have you checked and upped your tire pressures? That's an easy one.

You're already doing DWB and DWL. Pulse and glide could be something to consider: as Sean wrote coasting in neutral is easy as long as your car doesn't mind (and they usually don't).

Obviously, you can try lowering your speed where possible: time is money (though it can be better to use the time for other things).
Route planning and time planning can help you find better routes and lighter traffic.
Shed unnecessary weight from your vehicle.

Oh, and remember that the NEDC tests are really bad and are particularly bad for smaller-engined cars that are driven at speed.

Edit: I'll just scrap the acceleration bit.

Welcome back to the site! We have at least one very experienced diesel hypermiler in residence (Groar is his username and I'm sure he'll chime in very soon!).

One thing I can suggest right off the bat is to coast in Neutral instead of in gear. Unless your vehicle is one of those really interesting ones that "freewheels" when you let up off of the accelerator (I think the VW Polo eco model will do this?) you'll be slowing down in gear because of deceleration fuel cut and engine braking. Try shifting to neutral and see if you are able to glide further. Using no fuel but slowing loses out to idling usage but still coasting.

As for acceleration, you will get better numbers with brisk acceleration if you are using pulse and glide. If not (and it does not sound as though you are), slow acceleration is better.

Other than that your description of actions to take is right on.

What sort of time / distance are your trips? Stop and go or more of a steady cruise? Short trips with a cold engine really seem to kill my mileage. Stop-and-go in those situations makes it even worse.

I knew I was forgetting someone else closer to home. Sorry about that, Mike. :o

I would question limiting the revs to 1500. That will help you avoid boost, but will cost you in other ways. You'll be accelerating so gradually* that you'll be spending WAY too much time in the low gears, which is going to be counterproductive for fuel economy.

* in a turbodiesel it is CRITICAL to avoid heavy throttle below 1500rpm or so, because lugging the engine generates lots of soot, which clogs your intake (hundreds of $ to clean, at least with VWs) and can trash your turbo. You'll need to drive pretty carefully to avoid damaging your vehicle if you are seriously limiting your revs to 1500.

I think the general agreement, at least with VW TDIs, is to keep the revs below the 2000-2200rpm range. You'll get better mileage because (1) your engine generates power more efficiently in the 1500-2000 range anyway than it does below 1500, and (2) you'll more quickly accelerate into taller, more efficient gears.

I think I remember reading that brief hard acceleration in lower gears until you get up to speed is actually more efficient than slow acceleration, for diesel cars, but it seems counter intuitive. Any advice on that point?My view is that brief brisk (NOT hard) acceleration is most efficient. The rule about low gears being inherently inefficient is still true of diesels. You want to use enough throttle to move through the gears fairly quickly, but not so much that you generate full boost. A bit of boost probably can't be avoided and is a reasonable tradeoff.

Thanks for the welcome (back) and all the great advice above.

I should have stated above as I guess they're not available in the US... SEAT is a Spanish brand and manufactured (largely) in Martorell, just outside Barcelona, but it's part of VAG together with Audi, VW, Skoda, etc... so Leon mk2s like mine are essentially Golf 1.6 Bluemotions in terms of tech and mechanicals.

My typical commute is about 40 miles consisting of about 40% twisty country lanes, 30% A-road / dual carriageway and 30% slow traffic and stop-start queues as I get close to work. Obviously the same in reverse order on the way home.

Tyre-wise, the car came new with Pirelli P7 tyres (205/55 R16), which are supposedly LRR although I think I prefer the Goodyear EfficientGrip LRR tyres that I had on my last car for a while. At the moment though, I'm running winter tyres; we had a very cold (for here) start to the winter this year. I was careful to choose supposedly 'eco' winter tyres though: I'm using Michelin Primacy Alpin PA3s on the back and bought a pair of ContiWinterContact TS830s recently for the front axle (as my front Michelins got down to the snow wear markers).
Pressure-wise, I'm running 41psi all round. It's basically the top-end of the filler cap recommendations to use when fully loaded (but my car's usually just got me and my daughter in it, with a partly-loaded boot). This is considerably higher than the standard pressures for non-eco Leons, but under the maximum stated on the side wall.

@WriConsult: I think you've hit the nail on the head there - I tried accelerating 'briskly' through the first two gears this morning, changing at about 2,200 revs rather than 1,500 (which is almost painfully-slow to gain much speed especially up hill) and got much better figures than I have been. If I've been putting my engine/turbo at risk by changing too early, then all the more reason to put my foot down a little more initially!

Overall, my commute this morning felt quicker, more fun and involving than usual, simply by getting up to speed a bit quicker. I also upped my target speed for DWL from about 52 (~ 1,200 revs in 5th/top gear) to 62 mph (~ 1,750 revs) and was amazed to see that it didn't bring my usual figures down much, if at all.
Can't believe I didn't work that out for myself but I've been thinking slower driving = better mpg every time... obviously there are a few exceptions to that rule! ;)

@Sean: I will try coasting in neutral more over the next few days and hope to see some results from that too.

@Sean: I will try coasting in neutral more over the next few days and hope to see some results from that too.

In my gas Civic I noticed a significant difference on my commute that I would attribute mainly to NICE-ON. Easily got spring tanks of 44mpg, probably up from 38mpg. It's hilly around here... I think you'll see a quick benefit.