Omega Owners Forum

Chat Area => General Car Chat => Topic started by: 05omegav6 on 19 January 2014, 21:01:20

Title: LPG mpg and cost per mile Q...
Post by: 05omegav6 on 19 January 2014, 21:01:20
If a given version of a car does 20mpg, and petrol costs £1.30, I make that 30ppm...

If the same car does 18mpg on lpg, which costs £0.75, I make that 18ppm...

To put it another way, that's the same price as a diesel (£1.38) car doing 35mpg, ie 18ppm, but without a DMF, DPF or stupidly expensive fuel system.

What have I missed :-\
Title: Re: LPG mpg and cost per mile Q...
Post by: TheBoy on 19 January 2014, 21:04:41
Still uses a bit of petrol on the (fuel heavy) startup.

Savings are usually said to be around a third, so your figures aren't far off.
Title: Re: LPG mpg and cost per mile Q...
Post by: Entwood on 19 January 2014, 21:05:28
If a given version of a car does 20mpg, and petrol costs £1.30, I make that 30ppm...

If the same car does 18mpg on lpg, which costs £0.75, I make that 18ppm...

To put it another way, that's the same price as a diesel (£1.38) car doing 35mpg, ie 18ppm, but without a DMF, DPF or stupidly expensive fuel system.

What have I missed :-\

Not a lot ... small amount of petrol on startup, and cost of LPG conversion .. but right ball park

EDIT . must type faster .. :)
Title: Re: LPG mpg and cost per mile Q...
Post by: TheBoy on 19 January 2014, 21:05:38
On the 3.2, I struggle to exceed 17mpg though. Mrs TB can usually get close to 21mpg.
Title: Re: LPG mpg and cost per mile Q...
Post by: TheBoy on 19 January 2014, 21:06:51
I have my figures for TBE since I got it - petrol and LPG - but it syncs to PC upstairs, and thats switched off.

I could post tomorrow if I remember, if it helps?
Title: Re: LPG mpg and cost per mile Q...
Post by: Entwood on 19 January 2014, 21:10:10
My actual is running at 17.12 pence/mile against an estimated 27.63 pence/mile if I was using petrol , and thats over 60,000 miles, around 10 pence/mile saving

On a far shorter run - yesterday - 190 miles - the saving was 14.82 pence /mile, but it was a sedate motorway cruise at around 60 most of the time, following a mate in his van .. :)
Title: Re: LPG mpg and cost per mile Q...
Post by: 05omegav6 on 19 January 2014, 21:10:32
So hypothetically speaking, in fuel terms at least, this...

 http://www.autotrader.co.uk/classified/advert/201401130998664/sort/default/usedcars/model/vxr8/postcode/rh202dg/page/1/make/vauxhall/radius/1501/onesearchad/used%2Cnearlynew%2Cnew?logcode=p  (http://www.autotrader.co.uk/classified/advert/201401130998664/sort/default/usedcars/model/vxr8/postcode/rh202dg/page/1/make/vauxhall/radius/1501/onesearchad/used%2Cnearlynew%2Cnew?logcode=p)

Should cost the same to run as this...

 http://www.autotrader.co.uk/classified/advert/201401100942774/sort/default/usedcars/radius/1501/engine-size-cars/3l_to_3-9l/body-type/estate/model/vectra/maximum-age/up_to_6_years_old/fuel-type/diesel/page/1/onesearchad/used%2Cnearlynew%2Cnew/make/vauxhall/postcode/rh202dg?logcode=p  (http://www.autotrader.co.uk/classified/advert/201401100942774/sort/default/usedcars/radius/1501/engine-size-cars/3l_to_3-9l/body-type/estate/model/vectra/maximum-age/up_to_6_years_old/fuel-type/diesel/page/1/onesearchad/used%2Cnearlynew%2Cnew/make/vauxhall/postcode/rh202dg?logcode=p)

Have I missed anything else :-\
Title: Re: LPG mpg and cost per mile Q...
Post by: Entwood on 19 January 2014, 21:19:47
Using the urban cycle figures....

mmmm the Vectra does 28.8 mpg = (1.30 x 4.54)/28.8 = 16.24 pence /mile

The VXR8 does 13.7 mpg on petrol .. approx 10.96 mpg on LPG  (20% less) = (0.72 x 4.54)/10.96 = 29.8 pence / mile  so not quite close ...  (but closer than the VXR8 on petrol (1.3 x 4.54)/13.7 = 43.08 pence /mile  :) )

Not quite "Should cost the same to run as this.." IMHO .. :)
Title: Re: LPG mpg and cost per mile Q...
Post by: chrisgixer on 19 January 2014, 21:23:55
I guess, provided the first is not driven above the performance level of the second....

But how likely is that...? ;D.   Although traffic will dictate no doubt.

(The vxr8 will eat tyres though with an LSD, surely? And brakes may have similar intervall, but are 3times the cost. Worth it though, I'd say)
Title: Re: LPG mpg and cost per mile Q...
Post by: 05omegav6 on 19 January 2014, 21:28:34
Using the urban cycle figures....

mmmm the Vectra does 28.8 mpg = (1.38 x 4.54)/28.8 = 21.75pence /mile

The VXR8 does 13.7 mpg on petrol .. approx 10.96 mpg on LPG  (20% less) = (0.72 x 4.54)/10.96 = 29.8 pence / mile  so not quite close ...  (but closer than the VXR8 on petrol (1.3 x 4.54)/13.7 = 43.08 pence /mile  :) )

Not quite "Should cost the same to run as this.." IMHO .. :)
Fixed as the Vectra is diesel... the 20mpg on petrol, 18mpg on gas, is based on a known auto averaging 16 (calculated) on lpg, given the actual car in mind is a manual, (link was for illustration purposes in both cases) :y
Title: Re: LPG mpg and cost per mile Q...
Post by: Sir Tigger KC on 19 January 2014, 21:30:21
Have I missed anything else :-\

The VXR8 might not be suitable for taxi work?  :-X  :-\  ;)
Title: Re: LPG mpg and cost per mile Q...
Post by: 05omegav6 on 19 January 2014, 21:33:01
Have I missed anything else :-\

The VXR8 might not be suitable for taxi work?  :-X  :-\  ;)
Loads of room in it and a massive boot... what more is required ::)

Besides, it's hypothetical...
Title: Re: LPG mpg and cost per mile Q...
Post by: chrisgixer on 19 January 2014, 21:38:15
Using the urban cycle figures....

mmmm the Vectra does 28.8 mpg = (1.38 x 4.54)/28.8 = 21.75pence /mile

The VXR8 does 13.7 mpg on petrol .. approx 10.96 mpg on LPG  (20% less) = (0.72 x 4.54)/10.96 = 29.8 pence / mile  so not quite close ...  (but closer than the VXR8 on petrol (1.3 x 4.54)/13.7 = 43.08 pence /mile  :) )

Not quite "Should cost the same to run as this.." IMHO .. :)
Fixed as the Vectra is diesel... the 20mpg on petrol, 18mpg on gas, is based on a known auto averaging 16 (calculated) on lpg, given the actual car in mind is a manual, (link was for illustration purposes in both cases) :y
Was going to ask auto or manual. But assumed manual.;)
Title: Re: LPG mpg and cost per mile Q...
Post by: Sir Tigger KC on 19 January 2014, 21:43:06
Have I missed anything else :-\

The VXR8 might not be suitable for taxi work?  :-X  :-\  ;)
Loads of room in it and a massive boot... what more is required ::)

Besides, it's hypothetical...

Hypothetically speaking wouldn't the LPG tank take up about 1/3 of the mahooooosive boot?  :D  ::)
Title: Re: LPG mpg and cost per mile Q...
Post by: 05omegav6 on 19 January 2014, 21:50:47
Have I missed anything else :-\

The VXR8 might not be suitable for taxi work?  :-X  :-\  ;)
Loads of room in it and a massive boot... what more is required ::)

Besides, it's hypothetical...

Hypothetically speaking wouldn't the LPG tank take up about 1/3 of the mahooooosive boot?  :D  ::)
Not if it's in the spare wheel well where the Full size spare used to sit, silly :P
Title: Re: LPG mpg and cost per mile Q...
Post by: Entwood on 19 January 2014, 22:03:32
Only question I would ask on the fuel consumption figures you use ... are they also from taxi's ?? or from more "normal" usage ?? I can see a taxi having much higher fuel consumption than a "normal" car .. in which case the LPG option becomes even more favourable .... the more you use the more you save ....
Title: Re: LPG mpg and cost per mile Q...
Post by: Sir Tigger KC on 19 January 2014, 22:07:27
Have I missed anything else :-\

The VXR8 might not be suitable for taxi work?  :-X  :-\  ;)
Loads of room in it and a massive boot... what more is required ::)

Besides, it's hypothetical...

Hypothetically speaking wouldn't the LPG tank take up about 1/3 of the mahooooosive boot?  :D  ::)
Not if it's in the spare wheel well where the Full size spare used to sit, silly :P

 :-[
Title: Re: LPG mpg and cost per mile Q...
Post by: 05omegav6 on 19 January 2014, 22:09:57
Indeed they are Nige :y

Every diesel car I've driven for work has settled at 35mpg, so that is the benchmark for that.

The lpg figures are from an earlier VXR8 that does a mixture of taxi work and hooning around, so broadly similar to my current use :y
Title: Re: LPG mpg and cost per mile Q...
Post by: 05omegav6 on 19 January 2014, 22:11:27
Have I missed anything else :-\

The VXR8 might not be suitable for taxi work?  :-X  :-\  ;)
Loads of room in it and a massive boot... what more is required ::)

Besides, it's hypothetical...

Hypothetically speaking wouldn't the LPG tank take up about 1/3 of the mahooooosive boot?  :D  ::)
Not if it's in the spare wheel well where the Full size spare used to sit, silly :P

 :-[

That was meant to be tongue firmly in cheek  :-[ spare can live in the garage :y
Title: Re: LPG mpg and cost per mile Q...
Post by: Entwood on 19 January 2014, 22:16:05
Indeed they are Nige :y

Every diesel car I've driven for work has settled at 35mpg, so that is the benchmark for that.

The lpg figures are from an earlier VXR8 that does a mixture of taxi work and hooning around, so broadly similar to my current use :y

In which case .. Vectra @ 35 mpg diesel = 18.16 pence / mile

VXR8 @ 18 mpg on LPG = 18.16 pence/mile ....

absolutely the same !!!  so a small amount of petrol every startup on LPG and the cost of the conversion to factor in ..

 :y :y :y
Title: Re: LPG mpg and cost per mile Q...
Post by: Sir Tigger KC on 19 January 2014, 22:18:46
Have I missed anything else :-\

The VXR8 might not be suitable for taxi work?  :-X  :-\  ;)
Loads of room in it and a massive boot... what more is required ::)

Besides, it's hypothetical...

Hypothetically speaking wouldn't the LPG tank take up about 1/3 of the mahooooosive boot?  :D  ::)
Not if it's in the spare wheel well where the Full size spare used to sit, silly :P

 :-[

That was meant to be tongue firmly in cheek  :-[ spare can live in the garage :y
That's OK, hypothetically you only need a can of squirty goo anyway!  ::)  :)
Title: Re: LPG mpg and cost per mile Q...
Post by: 05omegav6 on 19 January 2014, 22:22:27
Have I missed anything else :-\
The VXR8 might not be suitable for taxi work?  :-X  :-\  ;)
Loads of room in it and a massive boot... what more is required ::)

Besides, it's hypothetical...

Hypothetically speaking wouldn't the LPG tank take up about 1/3 of the mahooooosive boot?  :D  ::)
Not if it's in the spare wheel well where the Full size spare used to sit, silly :P

 :-[

That was meant to be tongue firmly in cheek  :-[ spare can live in the garage :y
That's OK, hypothetically you only need a can of squirty goo anyway!  ::)  :)
It's fine, I have AA cover, what's the worst that could happen ;D