Fuel Economy - What do you get out of a tank? (3rd gens only)

[Oggy]

What do I get out of a tank of petrol? About a weeks worth of fun.

I was just thinking that showing average speed along with fuel consumption would be a good way to compare different driving conditions.
My commuting returns an average speed of 25 to 30kph (I've been tracking it for about the last 10 fill ups)
I'm burning through 16L every 100km since fitting HM heaeders, but yeah, I'm in shitty traffic, stop start all the time and I'm a lead foot.
My average speed through the school zones, round abouts and 50 zones up to the main road (about 3km) is higher than when I get to the 80 zone because the "main road" is just full of cars & traffic lights that take 3 cycles to get through.

My only good news on my petrol bill is that I filled up at WW / Caltex and somehow scored a 43 cpl discount - paid $0.95 per L yesterday. This week will be my cheapest $/Km in the Magna since I owned it

[AWD_Geoff]

Graham,

I'm interested by your reference to fitting HM headers. Have you noticed a difference in fuel consumption since having them fitted? (I'm currently looking at getting some for my TL AWD.)

[macropod]

I'm interested by your reference to fitting HM headers. Have you noticed a difference in fuel consumption since having them fitted?

If you're hoping for the headers to pay for themselves via improved fuel economy, be prepared for a long wait. Suppose, for example, your present fuel consumption is 13l/100km @ $1.50/litre and you pay $900 for a fitted set. If you gain a 5% improvement in fuel economy (i.e. taking the average down to 12.35l/100km), it'll take 92,308km before you reach the break-even point. Granted, fuel prices are likely to increase, but you'll also be losing the interest you could otherwise earn on the $900.

[AWD_Geoff]

Thanks guys.
I've been familiar with extractors for a long time. The way I like to look at them is that they are a versatile modification. If a car is driven gently (no faster than before) then a slight improvement in fuel economy can usually be expected. If the extra power and willingness to rev are taken advantage of, then fuel consumption won't improve (and probably get worse). Vlad your reply more or less confirms this.
I was interested to know if someone who has fitted them to a 3rd gen Magna has any objective data.
Macropod good calcs. I'm not necessarily expecting to recoup all my money but to put it another way I'm not interested in engine mods that lead to worse economy. Have you had extractors fitted to a Magna?

[macropod]

I have a set of HM headers on order ...

[Oggy]

Graham,

I'm interested by your reference to fitting HM headers. Have you noticed a difference in fuel consumption since having them fitted? (I'm currently looking at getting some for my TL AWD.)

My fuel consumption has worsened, but traffic in my area has worsened at an increased rate - it's gone to the shitter.
Average speed on this tank of fuel just commuting to work is about 23kph now.

I think I need a motorbike, except I'm worried I'd kill myself once I got used to it.

I'll get it to the drag strip one day and see if it's affected my 400m time at all. Only other mod is new Kumho tyres replacing Chinese ones that came with the rims.