Tdi economy problem

[Red Head]

My 2002 150 TDI is only giving me about 38 mpg when driven around town. I've not had the car long but must admit I was expecting a lot more than that. I have just had it serviced with a new belt etc by a VW specialist and it has done 61k miles. I have had 18 inch alloys put onto the car, would this have an effect on the fuel economy or give a false reading?
Thanks

[phumy]

All depends on the "rolling radius" of the wheel now that you have 18's on it, ie what tyres are fitted now, is the RR the same or very close?

If you have 70 profile tyres on 18 inch rims then yes it will upset the speedo and probably the MPG figures

[leosayer]

38mpg around town is fine, you should be pleased.

18" wheels will be wider than standard, probably a stickier compound tyre and probably heavier so there may be an effect on fuel consumption, but I can't say how much.

The computer is not always accurate, and always overstates true mpg. To calculate it properly you need to get a calculator out....here's the procedure:

Brim the tank then reset the mileometer to 0
Use up the tank then brim it again taking a note of how many litres added and how many miles done
Reset the mileometer to 0

Go home and do the calculation:
miles travelled / litres used * 4.55
eg 380 / 50 * 4.55 = 34.58mpg

[IceBoy]

That consumption seems pretty good for around town !

My A6 - 2003 TDI gives around 39 with mostly motorway cruising ! OK I know it is bigger/heavier but 38 for the golf sounds pretty good.

IceBoy

[IceBoy]

I mean't 38 around town is good

[phumy]

Ive got a Golf Gti TDi 150 and i get around 40-42 around town and 50-55 on the motorway, sometimes a little more if im restricted to 70mph

[ukross]

I wouldn't worry. 38 around town is not bad. A couple of long runs will soon get the average up.

[Red Head]

I did a bit of research before buying one and found a lot of people saying they got 50 mpg give or take regardless of how they drove, obviously this isn't the case? Other than that, I'm really happy with the car

[nickfrog]

How can a car get the same mpg REGARDLESS of how it's driven ?

High revs / high speeds tend to use more fuel.

Try and ride the torque and change gears very early, it might help, and should not affect your progress.

You can actually make normal progress with that engine without using the throttle. The torque at idle is sufficient to go through the gears without labouring the engine. It's a bit extreme but try and do that once as it will give you an insight as to what this engine can do. Good luck.