Fuel Consumption Dropped

[Velocette]

Now call me a saddo if you like but I keep a log of fuel consumption and always brim the tank and record the miles from the tripmeter. Over the 8874 miles before the car (07 Mk II T Spirit) was serviced I averaged 55.37 mpg, in the 1443 mile since the fill up following the service (5th November) I have averaged 50.24 mpg, a drop of around 9%. This seems quite substantial to me, there has been no change of driver, route, normal use etc that could explain this. I tend to run the tyres on the high side, 42 front and 40 rear, and will check whether this was reduced at the service. It has of course been much colder just recently which may account for the drop but other than that I cant think what it might be. I did read on here something about different viscosity oils but my local main dealer serviced the car previously and I do find them to be very good indeed so would think it unlikely but not impossible that this may account for it. Still, 50+ mpg is not to be sneezed at and i know my former diesel Octavia would have been delivering 45mpg albeit driven a little harder. So not a deal breaker but as I bought the car for reasons of economy (and reliability and safety) any thoughts would be welcome.

Thanks, Velocette.

[wizzlon]

Now call me a saddo if you like but I keep a log of fuel consumption and always brim the tank and record the miles from the tripmeter. Over the 8874 miles before the car (07 Mk II T Spirit) was serviced I averaged 55.37 mpg, in the 1443 mile since the fill up following the service (5th November) I have averaged 50.24 mpg, a drop of around 9%. This seems quite substantial to me, there has been no change of driver, route, normal use etc that could explain this. I tend to run the tyres on the high side, 42 front and 40 rear, and will check whether this was reduced at the service. It has of course been much colder just recently which may account for the drop but other than that I cant think what it might be. I did read on here something about different viscosity oils but my local main dealer serviced the car previously and I do find them to be very good indeed so would think it unlikely but not impossible that this may account for it. Still, 50+ mpg is not to be sneezed at and i know my former diesel Octavia would have been delivering 45mpg albeit driven a little harder. So not a deal breaker but as I bought the car for reasons of economy (and reliability and safety) any thoughts would be welcome.

Thanks, Velocette.

I started a thread here a while ago as my consumption dropped off. Conclusion is that it's cold weather.

[FourFourTwo]

Here ya go.

http://alternativefuels.about.com/od/hybridvehicles/a/hybridfuelecon.htm

[Velocette]

Oh I see, thanks for that. A useful tip about losing some of that unsightly flab as well. Roll on spring! Velocette

[Dave R.]

Oh I see, thanks for that. A useful tip about losing some of that unsightly flab as well. Roll on spring! Velocette

Well, you may think its the cold weather, but I too have experienced increased fuel consumption since the last service - though mine has been complicated by getting 3 new tyres immediately after the service. Unfortunately I'm a saddo too when it comes to logging fuel consumption, so I know every drop of petrol that has gone into my car (Gen III Tspirit) since it was new (October 09), 34,000 miles ago. IF you take a look at my Fuelly stats, you'll see that all through last winter (with temperatures down at minus 10 degrees C) I was getting between 49 and 50 mpg. Since my service in mid October, I've been struggling to get over 50 mpg.... the last tank was an all-time low of 46! now I know it has got colder but not THAT cold yet! Something is different.... the "warm up" consumption according to the computer (i.e. mpg after about 2 miles from cold) used to be around 45 mpg - now it is around 38. Similarly, if I get up to 60mph on a reasonably flat country road, the car can't maintain its speed unless consumption is hovering around 50mpg.

Is this all due to the rolling resistance of the tyres; is there some engine fault; have Toyota reprogrammed the engine management system?

Currently looking forward to getting a couple of punctures so that I can justify 2 or 3 new (different!) tyres!

[Ancient Nerd]

Oh I see, thanks for that. A useful tip about losing some of that unsightly flab as well. Roll on spring! Velocette

Well, you may think its the cold weather, but I too have experienced increased fuel consumption since the last service - though mine has been complicated by getting 3 new tyres immediately after the service. Unfortunately I'm a saddo too when it comes to logging fuel consumption, so I know every drop of petrol that has gone into my car (Gen III Tspirit) since it was new (October 09), 34,000 miles ago. IF you take a look at my Fuelly stats, you'll see that all through last winter (with temperatures down at minus 10 degrees C) I was getting between 49 and 50 mpg. Since my service in mid October, I've been struggling to get over 50 mpg.... the last tank was an all-time low of 46! now I know it has got colder but not THAT cold yet! Something is different.... the "warm up" consumption according to the computer (i.e. mpg after about 2 miles from cold) used to be around 45 mpg - now it is around 38. Similarly, if I get up to 60mph on a reasonably flat country road, the car can't maintain its speed unless consumption is hovering around 50mpg.

Is this all due to the rolling resistance of the tyres; is there some engine fault; have Toyota reprogrammed the engine management system?

Currently looking forward to getting a couple of punctures so that I can justify 2 or 3 new (different!) tyres!

Check that they didn't use 5W-30 oil at the last service, instead of 0W-20. I think the general experience is that it can make the sort of drop you are describing. I had the dealer drain and refill mine at it's first service. Grumpy Cabbie had to do the same, and I think has described the effect in considerable detail.

Tyres can also do it, especially if you don't get low rolling resistance tyres.

[Jan&tone]

Ancient... 0w-20 is for the gen3. According to the manual the gen 2 should have 5w30 in it.

The increased consumption is very likely to be a mix of new tyres and the use of fan/heater/aircon/heated rear window/lights etc, all things that would not necessarily be used in the summer, and all things that use power therefore using more petrol.

As someone else said "roll on spring"

[Bike Nut]

Oh I see, thanks for that. A useful tip about losing some of that unsightly flab as well. Roll on spring! Velocette

Well, you may think its the cold weather, but I too have experienced increased fuel consumption since the last service - though mine has been complicated by getting 3 new tyres immediately after the service. Unfortunately I'm a saddo too when it comes to logging fuel consumption, so I know every drop of petrol that has gone into my car (Gen III Tspirit) since it was new (October 09), 34,000 miles ago. IF you take a look at my Fuelly stats, you'll see that all through last winter (with temperatures down at minus 10 degrees C) I was getting between 49 and 50 mpg. Since my service in mid October, I've been struggling to get over 50 mpg.... the last tank was an all-time low of 46! now I know it has got colder but not THAT cold yet! Something is different.... the "warm up" consumption according to the computer (i.e. mpg after about 2 miles from cold) used to be around 45 mpg - now it is around 38. Similarly, if I get up to 60mph on a reasonably flat country road, the car can't maintain its speed unless consumption is hovering around 50mpg.

Is this all due to the rolling resistance of the tyres; is there some engine fault; have Toyota reprogrammed the engine management system?

Currently looking forward to getting a couple of punctures so that I can justify 2 or 3 new (different!) tyres!

Hello DaveR, my T4 which has done 5.5K miles at the moment is only returning high 40's low 50's at the moment and has not been serviced or had a tyre change. Since the colder weather has come along I also seem to struggle to maintain my speed unless the MPG bar is near or in the power zone. Just a comment as I seem to be returning similar figures to you but had no service or tyres.

[Grumpy Cabbie]

Yep, the gen 2 should use 5w30, it's the gen3 that is very sensitive to only using 0w20 oil.

I recon its the cold weather that is causing the lower mpg's but also I'd be curious as to what tyres you've put on. The Prius (of both gens) is susceptible to mpg loses if you don't use eco (low rolling resistance) tyres. I found this out early on when my fronts were replaced with what both my garage and I thought were the correct type of tyre and my fuel economy bombed. The tyres were then changed to Bridgestone Ecopias (their low rolling resistance tyre) and the economy when back up again.

So, check you've got low rolling resistance tyres - the extra cost is covered by the future fuel savings and as an interim measure check the tyre pressures - as many garages get it wrong and it makes a big difference to a Prius.

Hope this helps.

[Dave R.]

Oh I see, thanks for that. A useful tip about losing some of that unsightly flab as well. Roll on spring! Velocette

Well, you may think its the cold weather, but I too have experienced increased fuel consumption since the last service - though mine has been complicated by getting 3 new tyres immediately after the service. Unfortunately I'm a saddo too when it comes to logging fuel consumption, so I know every drop of petrol that has gone into my car (Gen III Tspirit) since it was new (October 09), 34,000 miles ago. IF you take a look at my Fuelly stats, you'll see that all through last winter (with temperatures down at minus 10 degrees C) I was getting between 49 and 50 mpg. Since my service in mid October, I've been struggling to get over 50 mpg.... the last tank was an all-time low of 46! now I know it has got colder but not THAT cold yet! Something is different.... the "warm up" consumption according to the computer (i.e. mpg after about 2 miles from cold) used to be around 45 mpg - now it is around 38. Similarly, if I get up to 60mph on a reasonably flat country road, the car can't maintain its speed unless consumption is hovering around 50mpg.

Is this all due to the rolling resistance of the tyres; is there some engine fault; have Toyota reprogrammed the engine management system?

Currently looking forward to getting a couple of punctures so that I can justify 2 or 3 new (different!) tyres!

Check that they didn't use 5W-30 oil at the last service, instead of 0W-20. I think the general experience is that it can make the sort of drop you are describing. I had the dealer drain and refill mine at it's first service. Grumpy Cabbie had to do the same, and I think has described the effect in considerable detail.

Tyres can also do it, especially if you don't get low rolling resistance tyres.

Thanks - already had WWIII about the oil (arguments about what the Dealer vs the Leasing Company vs Toyota say is the correct oil) Ended up getting the oil drained and changed after the service. Guess it must be the tyres and the weather :(