getting the best mpg out of my 1.7 sdi?

[joshuaspragg]

i was just wondering how to get the best out of my sdi for miles.

like what would be the best speed to go on the motorways for the most mpg? what other things could i do to get more out of it?

everyone was saying they can get like 400+ miles out of a tank

[JoeA]

Service it. Shed weight, rear seats, spare wheel. Then stick to around 60mph on the motorway and be smooth.

[John90]

As someone who has managed 140mpg in a Lupo (admittedly I did very little which is key), here are my tips. Driver intelligence can compensate for a lot of weight reduction, I wouldn't go crazy on that.

I have the Lupo 3L, (1.2 tdi) the super eco version, it stays in low gears almost to the point where the car stalls before the robotic manual gearbox changes down. It also switches off the motor at traffic lights. Use full synthetic oil, make sure your battery is OK. The best I have had on a 15 mile trip is the 140mpg. Switzerland isn't flat, and the end point was at a slightly lower altitude (435m, vs 666 at the start), but not massively different. Doing the return trip, which included an overnight stop (cold start), park up for shopping, driving through a busy village stop at a zebra, traffic lights, turn left (box out of eco mode to for a quick turn left), back to the filling station for a top off, resulted in 98mpg average.

Interestingly crawling in traffic, say 5mph, ticking over in first, uses more fuel than at 20mph. Also going too slow wastes fuel, like cruising at 40mph.

With my car, keeping to less than 60mph on the flat doesn't noticeably save much, which was a shock, seems to make things worse. The car should almost find its own speed. I imagine a bigger engine is most efficient going a bit faster.

Tips: Try not to accelerate up hills, hit the hill at the speed you want to go up it, or even a little faster, and let the car naturally slow down, so at the top you are doing a bit less than in the middle. Have an idea how fast you want to go on the road ahead well in advance, and don't let the car behind push you faster than you want to go (let it pass if safe). Try not to brake, this is key, especially with a car version that isn't weight optimised, speed should fall away naturally. Accelerate on downward slopes where possible. Breaking early for lights and junctions is a good strategy, as it gives you more time to roll up to the junction, to plan a way through traffic, and the lights time to switch. What you want to avoid is a complete stop, rather than trying to glide through at 30, possibly having an accident (expensive, dangerous, etc.).

The wife, driving into town a lot, we live up on the hill, might only get 65 to 70mpg in winter (lights, rear demist). Also choosing the right tyre the German site ADAC.de lists winter and summer tyres, shows their braking in different weather conditions, and gives them a fuel economy rating.

Eco driving is an interesting sport in its self. There is of course a website for modders: http://www.ecomodder.com If you were modding it for motorways, a higher top gear, take off the body mouldings, perhaps lower it a bit, 3L style boot spoiler, more efficient tyres (keep an eye on pressures), and reshape the rear bumper to reduce drag round the tyres, underbody motor cover (if not present). Apart from the 5th gear, it would be interesting to know exactly how much the aero stuff helps at say 70mph.

Edited November 19, 2012 by John90

[Hazy]

^ All very good pointers that!

The SDI's biggest killer for good mpg is the aforementioned long hills and stop-starts around town, at 60mph+ it's certainly more efficient than at sub 30mph speeds. It's at it's best down the motorway -keeping in mind the good point about letting it find it's own speed, you'll find it'll only have merest sips of fuel at around 60-65mph. Probably faster than that if it's congested and you can (within reason) slipstream vehicles in front. I usually average around 57-65mpg on normal town/country routes, which can easily go up past 70mpg+ on long motorway runs.

I'll reiterate the bit about letting the car find it's own speed. I get annoyed by Sunday-esque drivers tootling around country lanes where I live at about 25mph, which kills the car's momentum, I can more or less see the fuel gauge going down! But yeah, tyre pressure, regular services (I can more or less tell when the Fuel/Oil filters need changing) do help. Also, having the throttle to the floor doesn't help, if you can keep it around ½ you'll use less fuel too.

I should be sticking the 3L front (and rear bumper if I can find one) on mine beforelong, so it'll be interesting to see what difference that makes.

[joshuaspragg]

ahh thats good points actually cheers.