Cleaner air, who can be against that?

[unbeliever]

At the moment I have a Qashqai diesel with stop/start..I've had it a year and done 37,000 miles..my average MPG over that time over all sorts of roads and traffic conditions is 63 mpg..seems reasonably efficient to me..

 

I have a Volkswagon diesel. I don't know the details, but the tax is £30/year.

It does about about the same mpg as your Qashqai, but doesn't have stop/start.

 

---------- Post added 14-12-2015 at 14:06 ----------

 

 

Do you have any experience of a stop/start system or are you just guessing?

 

 

Guessing. Hence the "perhaps".

[geared]

At the moment I have a Qashqai diesel with stop/start..I've had it a year and done 37,000 miles..my average MPG over that time over all sorts of roads and traffic conditions is 63 mpg..seems reasonably efficient to me..

 

but do you own an identical Qashqai without stop start to directly compare if it actually has any difference you your real world mpg??

 

 

We have it on our car, switched on or switched off it makes zero difference to real world mpg.

I expect it would in heavy traffic, but I'm not about to go out and sit for hours on end in said traffic to find out.

 

Do quite enjoy the £80 cheaper it is over the non-stop/start equipped one though.

[truman]

but do you own an identical Qashqai without stop start to directly compare if it actually has any difference you your real world mpg??

Doubt it.

 

We have it on our car, switched on or switched off it makes zero difference to real world mpg.

 

I expect it would in heavy traffic, but I'm not about to go out and sit for hours on end in said traffic to find out.

 

The computer says that stop/start has saved around 11kg of CO2 output this year.I don't suppose it's saved very much really..but it's not just about one car.....

[geared]

Depends on who programmed the computer to say that though, the car doesn't actually know how much CO2 it's throwing out, the lambda sensor isn't that accurate.

[truman]

Depends on who programmed the computer to say that though, the car doesn't actually know how much CO2 it's throwing out, the lambda sensor isn't that accurate.

 

Well,it's obviously saving some on account of it turning off ... I assume it knows how much fuel it would use when idling (not very much) and knows how long it's been turned off so it's not a really difficult calculation to work out the CO2 saving..

Edited December 14, 2015 by truman

[DnAuK]

but do you own an identical Qashqai without stop start to directly compare if it actually has any difference you your real world mpg??

 

 

We have it on our car, switched on or switched off it makes zero difference to real world mpg.

I expect it would in heavy traffic, but I'm not about to go out and sit for hours on end in said traffic to find out.

 

Do quite enjoy the £80 cheaper it is over the non-stop/start equipped one though.

 

I can never understand why people expect the stop/start system to improve MPG. The engine only stops when you have, hence no miles, and no gallons. No different from sitting parked on your driveway. Sure, if you regularly do a lot of heavy traffic driving you will get a tiny benefit as you won't be wasting fuel while queuing. But most modern engines use so little fuel during this time that it's barely significant.

 

The only benefit of stop/start is emissions, and hence tax bracket. My car has stop/start. Engine cuts off seamlessly when out of gear below 12MPH and starts again immediately as soon as I put my foot on the clutch. It seems to work just fine. And as a result I pay no tax and those people walking and cycling past me get slightly less poisoned. But that is the only benefit.

[truman]

I can never understand why people expect the stop/start system to improve MPG. The engine only stops when you have, hence no miles, and no gallons. No different from sitting parked on your driveway. Sure, if you regularly do a lot of heavy traffic driving you will get a tiny benefit as you won't be wasting fuel while queuing. But most modern engines use so little fuel during this time that it's barely significant.

 

The only benefit of stop/start is emissions, and hence tax bracket. My car has stop/start. Engine cuts off seamlessly when out of gear below 12MPH and starts again immediately as soon as I put my foot on the clutch. It seems to work just fine. And as a result I pay no tax and those people walking and cycling past me get slightly less poisoned. But that is the only benefit.

 

I agree..that's the biggest benefit..

[Obelix]

Well if the engine is not running of course the emissions are lower. This is a good thing no?

 

Not necessarily.

 

The catalytic convertor takes time to start working. So if you stop the car, and it cools, then when you start it again you run for a period with no catalytic effect as it's not warm enough.

 

If the engine had idled, you would have stayed hot and the NOx and CO emissions would be lower (but with more CO2 emission...)

[DnAuK]

Not necessarily.

 

The catalytic convertor takes time to start working. So if you stop the car, and it cools, then when you start it again you run for a period with no catalytic effect as it's not warm enough.

 

If the engine had idled, you would have stayed hot and the NOx and CO emissions would be lower (but with more CO2 emission...)

 

The stop/start system doesn't work until the engine has warmed up. And has already been said here, tends to automatically start the engine again after a minute or so whether you're stationary or not. So I'm guessing there are some sensors on the battery and cat which do this to prevent things running too low / cold.

[JFKvsNixon]

The stop/start system doesn't work until the engine has warmed up. And has already been said here, tends to automatically start the engine again after a minute or so whether you're stationary or not. So I'm guessing there are some sensors on the battery and cat which do this to prevent things running too low / cold.

 

It's almost like the people who designed the stop/start actually know what they're doing.