New MG ZS high fuel consumption and frosty glass shattering

tifo

Goudy said:

If I solely drive my car back and forth to work in London I get 27 to 30 mpg.

You are obviously using the car in heavy city, stop start traffic.

I'd be happy with 27-30 mpg. I'm in Lancashire.

It's mostly school and shopping.

On motorway constant 1 hour i'd get around 33-36 mpg.

tifo

jon81uk said:

I'm not a big car user, but just curious, why get a 3 litre engine when you will mainly be doing short journeys? Surely a much smaller cheaper to run engine would have been better?

Who's got a 3 litre engine?

This is a 1 litre turbo 3 cylinder.

jon81uk

tifo said:

jon81uk said:

I'm not a big car user, but just curious, why get a 3 litre engine when you will mainly be doing short journeys? Surely a much smaller cheaper to run engine would have been better?

Who's got a 3 litre engine?

This is a 1 litre turbo 3 cylinder.

Ooops I mis-read and got the numbers transposed.

born_again

tifo said:

At 873 miles.

Rather than look at the average on the screen. Which is worked out by dodgy Chinese software. Also check is not set to US mpg which is a lot lower than UK mpg.
Fill the car to the brim. Note mileage. 
Driver to nearly empty & fill to brim again

Miles divided by litres put in = X. X times 4.55 = MPG

But if you are mostly doing sub 5 mile trips. It will not be getting up to normal engine working temp.

tifo

born_again said:

tifo said:

At 873 miles.

Fill the car to the brim. Note mileage. 

Driver to nearly empty & fill to brim again

Miles divided by litres put in = X. X times 4.55 = MPG

This is what I do. Note full and empty. Calculate mileage from gallons given for money paid (using price per litre) and miles driven divided by gallons to give true mileage. It's always a bit lower than what's shown.

CoastingHatbox

Goudy said:

Look at the miles, time and average speed, (119 miles in 12hours 50 minutes = 9mph).

1300 Kg car with a not huge amount of torque; suspect that's going to use a bit of fuel in start-stop traffic.

Still fairly appalling fuel economy though.

tifo

CoastingHatbox said:

Goudy said:

Look at the miles, time and average speed, (119 miles in 12hours 50 minutes = 9mph).

1300 Kg car with a not huge amount of torque; suspect that's going to use a bit of fuel in start-stop traffic.

Still fairly appalling fuel economy though.

Absolutely. Not expected and not as promised. At purchase we did raise the small engine and power and were told it's fine nothing to worry about "it's turbocharged".

Goudy

It's turbo forces air into the cylinders at pressure.
A normally aspirated 1.0 litre will take in 1 litre of air in a cycle, which it then adds fuel at a ratio close to 1 part fuel to 14 parts air.

A turbo increases the air pressure entering the engine which increases the air in there, so it has to add more fuel to maintain the same ratio.
The effect of this is the engines capacity is larger than on the boot badge as at typical peak boost you are getting somewhere around 50% more air into the cylinders, so it needs 50% more fuel when it does.

The turbo will be variable, so it can alter the pressure of air entering the engine based on speed/load.
Pulling away and accelerating it will try and boost more air into the engine, so needs to add more fuel.
At a steady cruise when the car it up to speed it doesn't need as much boost so the turbo backs the boost off with a wastegate or altering the turbo's vanes, which means less air and less fuel.

This effect means at peak boost your engine is like a 1.5 litre or more and will use the same sort of fuel.
At a steady cruise it's back close to 1.0 litre again and will use that sort of fuel.

If you are constantly pulling away and stopping, this is where any engine is at it's most inefficient.
You are repeatedly using energy/fuel to get yourself and the car up to speed, then effectively turning that energy into heat via the brakes, but it's peak boosting all the time you accelerate so it adding up to 50% more fuel every time it does.

This is one of the drawbacks with small turbo engines, they are really quite efficient once up to speed, but can be very inefficient when stop start driving which is why your fuel economy is so bad, though on average they would usually be running more miles when they are more efficient than when not.

Unfortunately, your needs aren't really allowing the car to run when it's efficient, it's stuck in a cycle of accelerate and stop, accelerate and stop which is causing the car to peak boost all the time (so peak fuel) and then wasting that energy as heat, over and over which is hammering it's fuel economy.

You might have been better with a normally aspirated car or a hybrid (or even electric).
A hybrid recovers some of that wasted energy from braking and uses it to help when it's internal combustion engine is inefficient, like accelerating.
When it is up to speed they tend to run the internal combustion engine more effieciently as most run a mock Atkinson cycle rather than an Otto cycle.
This mock Atkinson cycle tends to extract more out of the engines power stroke at the cost of torque, but the electric motor takes care of that, so they tend to be more efficient on those stop start sort of trips.

tifo

Goudy said:

Unfortunately, your needs aren't really allowing the car to run when it's efficient, it's stuck in a cycle of accelerate and stop, accelerate and stop which is causing the car to peak boost all the time (so peak fuel) and then wasting that energy as heat, over and over which is hammering it's fuel economy.

You might have been better with a normally aspirated car or a hybrid (or even electric).

Yes, a non turbo might have been better, but the exclusive trim with auto only comes with the 1 litre turbo engine. Buying the 1.5 non turbo would have meant no automatic, I think that's what we were told.

In any case, we were told the 1 litre is better than the 1.5, more efficient and power.

It was a choice between the Dacia Sandero Stepway premium or the MG ZS exclusive. The MG was at 0% interest last year so that did it. And someone cancelled this car on the day we went to order and wait 6 months so we got it a few days later after the reg application.

None of the reviews for this car said it was this bad in fuel and quality. There's many small niggles with it, bearable but not something i'm used to.

tifo

Before this I had a 1.6 Hyundai petrol and that did 30 mpg local. Non turbo.