VW Passat 1.9TDi Manual

Discussion in 'Start Your Journey Here' started by MikeMarsUK, Jan 8, 2008.

  1. MikeMarsUK

    MikeMarsUK Well-Known Member

    I've got a year 2000 VW Passat 1.9 TDi (115bhp) 5 speed manual. The engine and car is very similar to my last one (a 1996 Audi A4 1.9TDi 110bhp), but the VW has a trip computer which includes instantaneous, journey and trip MPG.

    Daily commute is 27 miles each way, comprising 3 urban miles, followed by 19 motorway miles, then finally five urban miles. I usually average between 52 and 55 mpg per tank (imperial), although my current tank mileage figures are 59MPG at 750 miles. Haven't had any major traffic jams on this tank, and also I've been doing longer trips over the holiday. Some times I mix in up to 25% vegetable oil with the diesel. Temperatures this winter are mostly between-2C and +10C.

    The official euro combined cycle figures for this car is 48MPG (imperial, of course).

    I find the main variable in MPG in my journeys is the journey length, as long as there are no long halts - at 5 miles (when the engine reaches normal temps) I'm only doing 45-48 mpg imperial (35mpg US). 10 miles = 50-53mpg, 20 miles = 52-56mpg, 50 miles = 60+mpg.

    I've read the hypermiling techniques, but to be honest I don't understand most of them :) Currently I just try to avoid braking by planning ahead, using the highest gear possible (for example, 1000rpm in 5th gear at 30mph when driving in a 30), following large vehicles (at about 1.5seconds) and don't push it too hard. The last is tricky because I'm very impatient :)

    I used to get 45MPG (35mpg US) in the Audi, probably because I used to cruise on the motorway at 95mph. It wasn't until I got the car with the trip computer that I could see how much difference it made to the MPG.

    I've installed low-rolling-resistance tyres on the back (Michelin Energy 3A. Front still have lots of tread). Any suggestions for the next step? I feel the biggest problem at the moment is during the five miles it takes the engine to warm up. Once I get to 5 miles I'm only at an average of 45mpg (35mpg us) or so. The rest of the journey's mpg is impacted by that initial section.

    I already do the following things:

    * DWB / smart braking - I've been (trying) to do this for years.

    * Drafting at about 1.5 seconds behind. The large vehicles here are limited to 56mpg. 1.5s seems enough time to be safe at that speed? Traffic side + surf aren't legal here because you're always supposed to be in the leftmost lane possible unless overtaking.

    I haven't tried any of the following things:

    * FAS =- (turning off engine and coasting?) - illegal here at most speeds. But if I'm in stop/go traffic on a steep downhill, sometimes I turn off the engine and let the car roll forwards as appropriate. Restarting a diesel engine costs more in fuel than a petrol engine (= 30 seconds idling).

    * Pulse and Glide. Not sure I understand this? Accelerate heavily, and then coast with engine turned off, repeat? Will this work for a diesel?

    * Warm up pulse and glide - if I understand this, it is start engine, join traffic, turn off engine and coast, restart engine, repeat until warm... won't this result in loads of cold starts? Would be quite tricky to do, junctions and traffic lights to navigate in the first quarter mile of my trip. (Sometimes the car will not restart for a few minutes if I stall the engine while it is still very cold. I guess this is because the glowplugs have cooled down but the engine management system thinks they are hot).

    * Potential parking - destination and start are on the flat.

    * Face-out - I do the opposite in winter to prevent frost getting on the windscreen. How much difference does it make in a trip?

    * Ridge riding - the white strip on the motorways here is a rumble strip intended to wake up sleeping drivers. But I try to avoid the groves in the road which the heavy vehicles cause (they can have a cm of rain in and make you aquaplane).
  2. xcel

    xcel PZEV, there's nothing like it :) Staff Member

    Hi Mike:

    ___Welcome to CleanMPG!

    ___All the items we talk about here work with a diesel as it does for a petrol fueled automobile or hybrid. It is the application that is different is all.

    1) Please be careful with the drafting stuff …

    2) FAS saves fuel no matter if it’s a diesel of petrol based automobile. Since you have a stick, you should consider clutch or “bump” starting as that does not burn any fuel. It does rob you of just a touch of kinetic however.

    3) P&G works on a diesel just as it does on a gas only vehicle. In fact, it will achieve even better results ;)

    4) Warm-up P&G should be used only where it is advantageous to do so. In heavy traffic and such, you have to be a little bit more delicate with what you can and cannot use. Alternate routes may help wrt that?

    5) PP should always be used. Instead of using your brakes to come to a stop, you glide ICE-Off to the highest point in the lot. If you come to a stop at the highest point facing the next direction of travel without using your brakes, you have completed the technique like a pro :) When you start out after your shopping or work, you do not start your engine but begin the glide down ICE-Off and if you have enough potential, clutch/”bump” start and being your next segment with an initial little FE buffer helping your journey.

    6) Face-Out is a must. Do this as an example. While your car is faced in, place your car in N and push it backwards and then forwards to get it heading in the direction of travel. All the energy you expended to pull out and face the proper direction is completely wasted unless you park Face-Out.

    7) RR. You got it for the rain and you do not ride on the rumble strips but right next to them.

    ___Get those tires pressed up and start practicing in a very efficient but safe manner. Why not start with following the speed limits, DWL, DWB and of course PP and Face-Outs. A TDI is easily worth 65 mpg US using the basics and a lot more with the advanced techniques.

    ___Although none of us would like to pay the petrol and diesel taxes/prices you do, we would all love to have access to the fuel efficient vehicles available to you. The following is just one reason why :D

    CleanMPG reviews the 2007 Honda Civic 2.2L iCDTi Turbo Diesel.

    ___Good Luck and welcome from all of us across the pond!

  3. MikeMarsUK

    MikeMarsUK Well-Known Member

    I'll give FAS a try when the roads are quiet (just in case I make a mess of it :) ), and the other techniques too. There's a 1.5 mile downhill I'll be doing tonight which will be a good candidate for FAS. I'll refuel + check tyre pressures today (should be at 59.2mpg imperial, my record so far for a tank). Will report progress at the end of the next tankfull.

    The Passat is quite a large/heavy vehicle in UK terms. (I think you call them 'wagons'?) I would have bought a Golf or Audi A2 or similar if I could but there were none on eBay with the right engine when I was looking for a car (I was in hurry...). Always better to buy a car when you have plenty of time!

    The engine in that Civic is roughly the same size/generation as my engine, but my car is bigger. I find the Polo BlueMotion quite an interesting vehicle, although I can't afford one for the next few years. It should return better results than the Civic? (euro combined figures are 72mpg imperial, so a good starting point). Has anyone given it a go?

    I'd love to see a hybrid based on the Polo BlueMotion... :)
  4. Blake

    Blake Well-Known Member

    I think everyone on this site would love to see a hybrid bluemotion polo in their driveway. I know I would :D

    as for safe following distance in drafting, it increases with your speed. I'd say that 1.5 seconds is only sufficent for speeds in the 40-45 mph range.. even thats probably pushing it. Back it on out to 3-5 seconds and be safe as you'll still get the benifit from the distant draft at those distances.
  5. WriConsult

    WriConsult Super Moderator

    Mike, thanks for posting and please keep us informed as to the progress with your efforts. I've just purchased a 2000 Golf TDI and hope to learn more about how to apply this stuff to diesels, having recently improved from 23 to over 30 miles per US gallon in a Subaru.

    Pulse and Glide (with the engine off) results in big benefits, but even Pulsing and Coasting (with the engine on) gives noticeable benefits in my experience. An engine might be using more fuel under moderate to heavy load than it does under light load, but it is putting out power more efficiently than under light load. What I often do is "pulse" up moderate hills and coast down them, sometimes for very big mpg benefits.
    Last edited: Jan 9, 2008
  6. MikeMarsUK

    MikeMarsUK Well-Known Member


    The pulse-and-coast, is that with the engine on but in neutral (at idle RPM), or with the engine on and in the highest gear available?

    I had a go tonight at driving up the hill, and rolling down with the engine off and in neutral. Does work very well, but my cars headlights dim (parking lights?) whenever the engine is off! As soon as I restart it by putting it into gear, the lights brighten up again. Managed 62mpg on a hilly 22 mile journey which usually gives me around 52-55mpg. (imperial figures, * 4/5 to get US).

    Congratulations on the Golf. You'll find you'll be using very low RPM (diesels pull very strongly in the low range). If it's manual, you can drive up a gentle hill in 5th gear with no throttle, just idle (around 25mph). I use 5th gear for a lot of city driving.


    Last edited: Jan 10, 2008
  7. MikeMarsUK

    MikeMarsUK Well-Known Member

    I've been working on the very basic techniques (slow speed, minimal braking, etc), ignoring the more complex hypermiling stuff for now, and I've managed to get to 64.1 imperial mpg on the Passat. This is roughly 53.4 us mpg. I've submitted this tank and the previous (poor tank due to various factors) one to the TDIClub march competition, although I'm way off the lead for the Passat class ('tdijoe' is winning at 57 mpg us).

    Last tank: 850.3 miles, 60.23 litres.

    First tank
    Second tank

    The average between the two tanks would be around 50.4 us mpg.

    These are what I am currently doing:

    * Steady load (within speed boundaries, for example 50-60 on the motorway)

    * DWB / smart braking

    * Drafting at about 1.5 seconds behind.

    * 'face out' when parking

    * 50mph on the motorway if safe. 55 mph if I'm in a 60 zone and a single carriageway (if people can't overtake).

    * Ridge-riding if very wet, but hasn't been so much rain recently

    I'm not doing the following

    * FAS

    * Pulse and Glide or any variations

    * Potential Parking - destination and start are on the flat so not possible
    Last edited: Mar 24, 2008
  8. corvette

    corvette just 1:18 ;-)

    Since the topic is about modern turbodiesel engine - how does it tolerate bump starts? Are there any potential downsides, such as (premature) DPF or Katalysator failure?

    (I know, it's an old topic and some dust removal was needed, but it's good to have things in one place)
  9. WriConsult

    WriConsult Super Moderator

    Haven't done too many bump starts on my TDI, though it seemed to work fine when I did it. Honestly, diesels idle so efficiently I rarely bother killing the engine.

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