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Average mpg

stephen watson

stephen watson

Messages
198
Location
Cumbria
Vehicle
T6 Ocean 150
I have a two and a half year old 150 Beach. I've been keeping detailed mpg figures for the past 18 months. Even fully laden touring Europe with four bikes I had excellent mpg figures. It dropped slightly when we moved back to London, and even more so when we changed from 215 tyres to 235 tyres. We are hoping it will now improve as we have bought a small car for shorter trips.

The MFD consistently gives better fuel consumption figures than fill to fill measurements.

DateKilometresLitresMPG (fill to fill)MPG (MFD)
Touring Europe
3 Feb 1882768.5434.08
8 Feb 18106180.2937.33
18 Feb 1876664.7233.43
28 Feb 18100881.3335.01
13 Mar 18100971.1640.05
22 Mar 18102372.4939.86
31 Mar 1891169.3837.09
6 Apr 1883969.0034.45
13/16 Apr 18142299.0140.57
1 May 1882467.0334.73
13 May 1873965.4631.89
19 May 1874559.2335.53
27 May 1889369.5036.30
4 June 1870665.0030.68
8 June 1889376.1633.12
Returned to London
22 June 1882369.2933.55
28 June 18106274.1240.47
4 Jul 1885869.0135.12
18 Jul 1855554.1328.96
24 Jul 1894872.0337.18
10 Aug 1879267.7233.04
16 Aug 1890668.4737.38
21 Aug 1893371.5736.82
1 Sep 1887672.7834.00
16 Sep 1880171.1531.80
28 Sep 1871665.0031.12
10 Oct 1879269.0032.42
23 Oct 1889274.4933.83
3 Nov 1892273.3935.39
20 Nov 1893573.5835.90
26 Nov 18108373.3941.69
11 Dec 1876570.0030.87
Service and new wheels and tyres17" replace 16"
235 replace 215
27 Dec 1867171.8426.38
13 Jan 1976970.3630.87
1 Feb 1969572.2827.16
18 Feb 1972170.5428.87
6 Mar 1983472.2032.63
16 Mar 1990371.1735.8440.5
5 Apr 1962467.5026.1129.4
16 Apr 1983570.9933.2337.1
11/16 May 1990892.0327.87
23 May 1984381.5029.2229.4
25 May 1974969.9130.2631.1
1 June 1998076.4236.2337.8
12 June 1983367.6234.8036.8
25 June 1976276.6928.0730.9
Bought 2nd car for shorter journeys
18 July 1974074.0028.2531.1
4 Aug 1978272.2830.5633.2
16 Aug 1993571.1037.1538.9
20 Aug 1989581.4531.0432.5
31 Aug 1984568.0035.1036.7
Hi Tom
Bit confused by your comment that your mpg has dropped since you went to 235 tyres. My understanding is that the 2 sizes available on the Ocean (215/60 and 235/55) have the same overall diameter on a 17" wheel, as although the 235 is a lower profile it is also wider. If you changed from your factory Beach 16" to 17" wheels this surely means that your speedo and odometer is now inaccurate and although it says your mpg is down it's not?
Please correct me if'm wrong - I'm not an expert. Like you I record my mpg (on Spritmonitor) and find the mfd is optimistic by around 10%. However although I know the amount of fuel is accurate I have always wondered if your speedo overheads by say 5%, which is common, does this also mean the odometer reading is not 100% accurate. Maybe you, or WG, know the answer?
 
clarinetbcn

clarinetbcn

VIP Member
Messages
176
Location
Barcelona, Spain
Vehicle
T5 Beach
Hi Tom
Bit confused by your comment that your mpg has dropped since you went to 235 tyres. My understanding is that the 2 sizes available on the Ocean (215/60 and 235/55) have the same overall diameter on a 17" wheel, as although the 235 is a lower profile it is also wider. If you changed from your factory Beach 16" to 17" wheels this surely means that your speedo and odometer is now inaccurate and although it says your mpg is down it's not?
Please correct me if'm wrong - I'm not an expert. Like you I record my mpg (on Spritmonitor) and find the mfd is optimistic by around 10%. However although I know the amount of fuel is accurate I have always wondered if your speedo overheads by say 5%, which is common, does this also mean the odometer reading is not 100% accurate. Maybe you, or WG, know the answer?
There is no difference in overall circumference of tire combinations mounted on 16” and 17” wheels. Tire sidewall on 17” is shorter, so gives the same overall dimension as a 16” with higher side wall. Speedometer and odometer are not affected. The difference in mileage is due to rolling resistance and possibly wind resistance.
 
2into1

2into1

Née T4WFA. Now running 2017 150 DSG Ocean
Lifetime VIP Member
Messages
2,899
Location
Glossop
Vehicle
T6 Ocean 150
Hi Tom
Bit confused by your comment that your mpg has dropped since you went to 235 tyres. My understanding is that the 2 sizes available on the Ocean (215/60 and 235/55) have the same overall diameter on a 17" wheel, as although the 235 is a lower profile it is also wider. If you changed from your factory Beach 16" to 17" wheels this surely means that your speedo and odometer is now inaccurate and although it says your mpg is down it's not?
Please correct me if'm wrong - I'm not an expert. Like you I record my mpg (on Spritmonitor) and find the mfd is optimistic by around 10%. However although I know the amount of fuel is accurate I have always wondered if your speedo overheads by say 5%, which is common, does this also mean the odometer reading is not 100% accurate. Maybe you, or WG, know the answer?
Edit - above post landed as I posted this
The rolling diameter of all 3 types is the same (to within small margins). The 235s have higher rolling resistance (think why racing cycles have rubber bands for tyres). They also run at lower pressures and I suspect that contributes too. The 215s on the 17" rims are usually Continentals with 109 load rating, very stiff walls, very low rolling resistance, but a harsher ride than the 235s.
 
Amarillo

Amarillo

Tom
Top Poster
VIP Member
Messages
5,089
Location
Royal Borough of Greenwich
Vehicle
T6 Beach 150
Hi Tom
Bit confused by your comment that your mpg has dropped since you went to 235 tyres. My understanding is that the 2 sizes available on the Ocean (215/60 and 235/55) have the same overall diameter on a 17" wheel, as although the 235 is a lower profile it is also wider. If you changed from your factory Beach 16" to 17" wheels this surely means that your speedo and odometer is now inaccurate and although it says your mpg is down it's not?
Please correct me if'm wrong - I'm not an expert. Like you I record my mpg (on Spritmonitor) and find the mfd is optimistic by around 10%. However although I know the amount of fuel is accurate I have always wondered if your speedo overheads by say 5%, which is common, does this also mean the odometer reading is not 100% accurate. Maybe you, or WG, know the answer?
The 16"/17" refers to the wheel. As far as I am aware the tyre diameters are either the same or close to the same. The 215/235 refers to the width, with the 235 having 20mm more rubber in contact with the road and thus more friction. The tread pattern may also make a difference to the friction.

I'm afraid that I do not know who the odometer measures distance. I expect it counts wheel revolutions and calculates distance by multiplying revolutions by tyre circumference.
 
clarinetbcn

clarinetbcn

VIP Member
Messages
176
Location
Barcelona, Spain
Vehicle
T5 Beach
There is no difference in overall circumference of tire combinations mounted on 16” and 17” wheels. Tire sidewall on 17” is shorter, so gives the same overall dimension as a 16” with higher side wall. Speedometer and odometer are not affected. The difference in mileage is due to rolling resistance and possibly wind resistance.
Your question about whether the odometer is just as inaccurate as the speedometer, independently of overall circumstances of wheel/tire combinations, is a very good one.
 
stephen watson

stephen watson

Messages
198
Location
Cumbria
Vehicle
T6 Ocean 150
The 16"/17" refers to the wheel. As far as I am aware the tyre diameters are either the same or close to the same. The 215/235 refers to the width, with the 235 having 20mm more rubber in contact with the road and thus more friction. The tread pattern may also make a difference to the friction.

I'm afraid that I do not know who the odometer measures distance. I expect it counts wheel revolutions and calculates distance by multiplying revolutions by tyre circumference.
I'm getting a bit confused now. For a 17" wheel the height of the tire is the width x profile. For 235/55 therefore 235x.55=129.25 and 216x.6=129.6
Therefore if you buy a beach with 16" wheels the speedo/odometer is set at the factory and if you subsequently change the wheel size to 17" it will make a difference as the overall diameter has decreased, irrespective of what profile tyre you fit.
 
stephen watson

stephen watson

Messages
198
Location
Cumbria
Vehicle
T6 Ocean 150
Sorry meant to say overall diameter has increased in above post
 
clarinetbcn

clarinetbcn

VIP Member
Messages
176
Location
Barcelona, Spain
Vehicle
T5 Beach
the height of the tire is the width x profile.
Don’t know where you got this formula, but not true. Overall hight is a result of wheel diameter and tire sidewall height. I think you may be confusing this with how the number for a tire profile is assigned, which is a formula based on the tire’s sidewall height and tread width.
 
clarinetbcn

clarinetbcn

VIP Member
Messages
176
Location
Barcelona, Spain
Vehicle
T5 Beach
Don’t know where you got this formula, but not true. Overall hight is a result of wheel diameter and tire sidewall height. I think you may be confusing this with how the number for a tire profile is assigned, which is a formula based on the tire’s sidewall height and tread width.
That means that two tires with identical sidewall height will have different profile numbers if the tread width is different. It’s the relationship between sidewall height and tread width which largely defines the handling characteristics of a tire, which is why the profile number is so important.
 
stephen watson

stephen watson

Messages
198
Location
Cumbria
Vehicle
T6 Ocean 150
This is what I was trying to explain. I agree that overall height is wheel diameter plus tire sidewall height. All I am trying to say is that the 235/55 and 216/60 tyres have almost identical tire sidewall height so if Tom has switched from 16" to 17" wheels that maybe why his mpg has dropped. As I said I'm not an expert.

Screen Shot 2019-09-07 at 18.14.47.png
 
B J G

B J G

VIP Member
Messages
1,930
Location
Stamford
Vehicle
T6 Ocean 204 4Motion
I'm getting a bit confused now. For a 17" wheel the height of the tire is the width x profile. For 235/55 therefore 235x.55=129.25 and 216x.6=129.6
Therefore if you buy a beach with 16" wheels the speedo/odometer is set at the factory and if you subsequently change the wheel size to 17" it will make a difference as the overall diameter has decreased, irrespective of what profile tyre you fit.
You seem to have got the relationship between wheel diameter and tyre profile confused, use this to clarify how the change from 16" to 17" wheels with the correct tyres fitted is virtually equal in speed terms.
215/65/16 is correct I believe not 216/60/16.
 
clarinetbcn

clarinetbcn

VIP Member
Messages
176
Location
Barcelona, Spain
Vehicle
T5 Beach
This is what I was trying to explain. I agree that overall height is wheel diameter plus tire sidewall height. All I am trying to say is that the 235/55 and 216/60 tyres have almost identical tire sidewall height so if Tom has switched from 16" to 17" wheels that maybe why his mpg has dropped. As I said I'm not an expert.

View attachment 50061
Maybe it would help to clarify that the whole point of increasing wheel size (not counting bling factor!) is to reduce sidewall height to improve handling. Tom’s choice was to reduce sidewall height, and to further improve handling by increasing tread width. He achieved both of these goals without changing overall height and diameter, but at a cost in mileage due to rolling resistance.
 
Last edited:
B J G

B J G

VIP Member
Messages
1,930
Location
Stamford
Vehicle
T6 Ocean 204 4Motion
Maybe it would help to clarify that the whole point of increasing wheel size (not counting bling factor!) is to reduce sidewall height to improve handling. Tom’s choice was to reduce sidewall height, and to further improve handling by increasing tread width. He achieved both of these goals without changing overall height and diameter, but at a cost in mileage due to rolling resistance.
It isn't a case of increasing tyre width & reducing side profile giving improved ride and handling as many car reviews highlight when comparing models fitted with the 'bling' big wheels compared to the more standard wheels fitted on that particular model.
Greatest improvement comes from the actual suspension, ie stiffer ARB's and spring plus damper upgrades which can be cheaper than a set of wheels and tyres. downside is they have no visible 'bling' factor.
As a tyre width increases the road contact area doesn't, wider yes but the front to rear reduces.
This review helps to clarify what is actually the gains-losses with width. A car test but helps to understand the issue.
 
clarinetbcn

clarinetbcn

VIP Member
Messages
176
Location
Barcelona, Spain
Vehicle
T5 Beach
It isn't a case of increasing tyre width & reducing side profile giving improved ride and handling as many car reviews highlight when comparing models fitted with the 'bling' big wheels compared to the more standard wheels fitted on that particular model.
Greatest improvement comes from the actual suspension, ie stiffer ARB's and spring plus damper upgrades which can be cheaper than a set of wheels and tyres. downside is they have no visible 'bling' factor.
As a tyre width increases the road contact area doesn't, wider yes but the front to rear reduces.
This review helps to clarify what is actually the gains-losses with width. A car test but helps to understand the issue.
Given the same suspension, lower profile reduces sidewall flex, leading to more rapid and precise response to steering input. Downside is that in general this leads to a harsher ride since the sidewalls have less flex to absorb shocks. Other variables such as tire pressure and tread width also have an influence, so this is not as black and white as it might seem.
 
B J G

B J G

VIP Member
Messages
1,930
Location
Stamford
Vehicle
T6 Ocean 204 4Motion
Given the same suspension, lower profile reduces sidewall flex, leading to more rapid and precise response to steering input. Downside is that in general this leads to a harsher ride since the sidewalls have less flex to absorb shocks. Other variables such as tire pressure and tread width also have an influence, so this is not as black and white as it might seem.
Precisely.
 
W

Wild Bob

Messages
59
Location
Bolton
Vehicle
T6 Ocean 150
Sorry if this has been covered before. My Ocean 150 dsg has only done a few hundred miles so the engine is still tight, but I'm only getting about 28 mpg. What are people getting when the engine loosens up?
My 150 dsg Ocean only done 100 miles and up to now showing 33 mpg :( but hoping this will improve when run it
 
Vantastic2

Vantastic2

Messages
80
Since my very first car I have been addicted to how much a vehicle does MPG(sad but 46 years on still doing it )
Well for a vehicle of 3,000 kg fully laden im please with what it does.(mine never fully laden)
Im on a very high hill so going dn when cold approx. 40 mpg, a 2 mile journey round trip to home from supermarket 23 mpg.(winter) (25 summer) and depending on how many stops made ie traffic light is green.
A trip of 50 mile had at one point 48 mpg ????? what the book says is im lucky to get 43mpg.
Fill her up to the brim take readings, fill her up again to same spot,done it so many times in the past before having a vehicle with a computer but found not much in the readings between Cali computer and the old test so rare do I do it now.
What im saying is, forget the figures VW give,( engine bench tested )its up to YOUR DRIVING and Maintenance of YOUR vehicle and lastly the terrain on where your travelling.
If anything try and beat them !
 
Ksar-el-kebir

Ksar-el-kebir

VIP Member
Messages
300
Location
East Northants
Vehicle
T6 Ocean 204 4Motion
If that's the computer figure, the real number is probably 25. Mine is the same spec and getting around 37 long term average (real not mfd) although I drive like a wuss.
I too drive conservatively. I had a 150 and it gave good mileage, 40+ and that was after not trusting the MFD. Now got 4motion with the larger engine; much less frugal!
 
S

Scarylion1

Messages
5
Just drove to Edinburgh and back from Watford on one tank 750 miles. Computer said i5 was averaging 45 mpg. 2013 Beach. Awesome.
 

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