Diesel vs Petrol?

[s-line stu]

Having started a new job this week I'm now commuting 130 motorway miles a day and my 1.8T (190) is averaging around 36 mpg and has 32K on the clock. So that's around £95 of fuel a week with a bit of social use thrown in.

My dilema is that while the milage is still fairly low I could chop it in for a B7 2.0TDI on around an 06-07 plate which should return around 45-50 mpg and may well be a more relaxed drive as TDI's rev lower - right?

My dilema is that the job is only contract so may last 3 months or may last 3 years. If I get a TDI then end up changing job to something nearer to home I've heard that short journeys are not good for TDI's.

What do you recon?

 

[BahnStormer77]

to answer the general diesel vs petrol question: they rev a LOT lower, but with a LOT more torque.... they will pull cleanly through from 1000-4000rom and are dead by 4500rm.... mine has more torque from 1500rpm-4000rpm than an RS4 (at peak!).... but mine stops at just over 4000rpm, while an RS4 continues through to >8000rpm

depends on which spec 2.0TDI... the 170PS's are actually the more economical and can be remapped to 190+ (I think some have got 220bhp just on a remap!?!?).

If it's a relaxed motorway cruise, you're looking at 60mpg+... you'll probably average 50mpg+ on a tank with a mix of driving, but it's even more dependant on driving style than with petrols!

My V6 2.5TDI quattro: which ISN'T a very fair comparison as it's a LOT heavier on fuel compared to the FWD 2.0TDI due to it being a big V6 lump, full quattro (weight and drivetrain resistance) and the previous generation of TDI, but I'll average around 35-40mpg (about 400 miles on the 50 litres, before it asks for more) and that's with a mix of town and A-road driving, but with a very gentle motorway cruise that range jumps to >600miles on the 50l, so around 55mpg.

I believe the 2.7TDI replacement to my 2.5TDI (which has the same stock power (180bhp), torque (370Nm) and "chippability") gets around 65mpg on an extra-urban cycle!

The 2.0TDI will be a lighter car, similar car (if you get the high spec one) and even lighter on fuel!

 

[s-line stu]

Just found this comparison guide that Parkers do. Unfortunately it's only for new cars but is still interesting, for example on a new diesel 2.0TDI A4 you'd have to do 32000 miles before it breaks even against a petrol 2.0TFSI A4.

http://www.parkers.co.uk/cars/petrol-vs-diesel/

 

[BahnStormer77]

it is pretty high mileage before it's really worth while.... but I just like the idea of a car that's really economical, but still has so much torque that you can put five people + luggage into it and it'll pull off the line exactly the same....

 

[s-line stu]

I agree, I think it's psychological, looking at the mpg and seeing 50+ must be pretty satisfying and I like the idea of a low reving torquey engine on the motorway as I think it would definately be a more effortless journey, not that the 1.8T is bad. Tax and insurance would be less too.

It really depends how long my contract is likely to last so I guess I'll give it a couple of months and if it looks like I'll be there for a while then I'll look into changing as it will work out at around 30,000 miles a year commuting.

 

[BahnStormer77]

it makes a much bigger difference if you have access to cheap / free chip-fat.... apparently even better if it's been used already....

most cars can handle it being mixed 50/50 with diesel.... or you can get one of those home "cracking" units that's looks like a waterbutt that sits in your garage and you pour the chip-fat (or mexican food, chinese food, etc frying fat) into the top and it gets strained, mixed with the right ratio of ethanol to give it the same properties of diesel.... without this, the oil it very close at room tempeprature, but not the right consistency at lower temperatures.

 

[The Slug]

i cant wait til they bring out the flux capasitor version pmsl.....ohh its all coming true

 

[BahnStormer77]

hey running a derv engine off used chip-fat is nearly full-scale Back To the Future as far as I'm concerned....

 

[offset]

just done a 600 mile round trip .......on a full tank ,with my a4 170 , sweet!!!!!

 

[BahnStormer77]

offset - the 2.0 170PS TDI's are the most efficient of the new TDI's... and the FWD version even better than the Quattro's so you should be able to do that at a fair old pace... if I keep the speed around 70mph, I could do 600miles in 50-odd litres in my 2.5TDI Quattro,so you should do that very easilly indeed!

 

[s-line stu]

I get around 560 miles out of a full tank with my commute which is mainly at 70-80 mph as it's 65 miles and all motorway.

 

[paul20v]

I average around 45-50 mpg .

 

[technics100]

Can people please put their actual mpg, as putting miles to a tank depends on how much fuel you put it. I always got around 40-42 mpg from my 130tdi with a tuning box in it. On the same run I'm getting about 33-35 mpg in my brothers 1.8T toledo, no a great difference and the toledo puts out 225bhp and is a good but quicker than the Tdi. With diesel being dearer than petrol there really isn't much in it.. I think I would stick with the quieter, quicker petrol engine..

 

[BahnStormer77]

technics - I know what you mean, however not everybody has the avg MPG option... but most people fill their tanks to the top and reset the trip computer, so the miles done "a tank" is the miles completed + miles remaining according to the trip computer... and then you have to rememebr that is what has been done on the 50 litres* before the trip computer says "0 miles remaining"...

It's a pretty easy sum: 50 litres = 11 UK gal (or VERY close!)

e.g. 660 miles on a tank / 11gal = 60mpg

So I work on a very approximate mental sum of miles done on a tank divided by 10 and minus just under 10%.... so 660miles would be 660/10= 66 and minus 6-ish... so 59.xmpg...

*The bit that screws that sum up is that somebody told be that they can put 60 litres in once their trip computer says "0 miles"?!? So maybe it's not such a great plan!

 

[technics100]

yeah, my past 2 A4 TDi's didn't have trip computers, I used to work it out by filling it up. and working miles done. Its easy if you start on a full tank, then reset your trip computer, then fill the tank at the next fill and work count miles done. e.g.

Fill tank to start
count miles done - 455
refill tank - 48 litres = 10.57 gallons
455 -:- 10.57 = 43mpg
then refill tank and reset odometer..

do again.. there are handy apps for the iphone that work all that out..

Not that it matters to me with the S6 managing about 18mpg :-(

 

[technics100]

yeah, my past 2 A4 TDi's didn't have trip computers, I used to work it out by filling it up. and working miles done. Its easy if you start on a full tank, then reset your trip computer, then fill the tank at the next fill and work count miles done. e.g.

Fill tank to start
count miles done - 455
refill tank - 48 litres = 10.57 gallons
455 -:- 10.57 = 43mpg
then refill tank and reset odometer..

do again.. there are handy apps for the iphone that work all that out..

Not that it matters to me with the S6 managing about 18mpg :-(

 

[quattrojames]

This mpg calculator does the hard work so you dont have to

LINK

My DIS says 34, and I actually achieve 36mpg.

 

[quattrojames]

*The bit that screws that sum up is that somebody told be that they can put 60 litres in once their trip computer says "0 miles"?!? So maybe it's not such a great plan!

I regularly get 60 litres in my tank with 20 or so miles left to go on the DIS. IIRC correctly the quattro avant tank is 66 litres, other models may vary