Expert answer

Hi Sean,

The answer really depends on the type of four-wheel drive you have. Most road-biased SUVs and crossovers with four-wheel drive apportion the engine output to the wheels with the most grip. Some won't use four-wheel drive unless slip is detected anyway. In those cars it makes sense to leave the car in four-wheel drive mode all the time, certainly in the snowy weather we have right now. Best to not get stuck rather than turning on the four-wheel drive when you might already be having an issue.

Some four-wheel drives have a 'differential lock', which makes sure that all the wheels receive equal amounts of power. That should only be used in really tricky conditions, as the car won't be very responsive to turning and the tyres would wear out quicker on a normal road in that mode.

Hope that helps, but feel free to ask us more.

Expert answer

Renault have come back to us with the information. 

The pressures in are front: 2.1 bar (30 psi)and rear 2.0 bar (29 psi) on the 225/55 R17s.

If you do a lot of motorway driving then these should be 2.2 bar (32 psi) front and 2.0 bar (29 psi) rear.

I hope this helps.

Expert answer

Hi Carl,

The thing about fuel economy figures from the manufacturer is that they are often very difficult to match. We seldom match them, as they are recorded using specific lab conditions and are often not really reflective of real-world conditions.

There are some things you can do to improve your fuel economy however:

1 Pump up to cut down 

Under-inflated tyres create more resistance. That means your engine has to work harder, so more fuel is used. Check and adjust your tyre pressures regularly, and also before long journeys.

2 Less clutter means less CO₂ 

Clutter in your boot is extra weight in your car. By removing it, you could reduce your engine's workload. This will burn less fuel.

3 Drive at an appropriate speed 

Staying at or within the speed limit not only increases driver safety, it also reduces fuel consumption. At 110km/h you could be using nine percent more fuel than at 100km/h, and up to 15 percent more fuel than at 80km/h.

4 Less stopping and starting 

Every time you stop then start again in a traffic queue the engine uses more fuel. Keep an eye on the traffic ahead and slow down early by gently lifting your foot off the accelerator while keeping the car in gear. The traffic may have started moving again by the time you reach the vehicle in front, so you can change up a gear and be on your way.

5 Over-revving accelerates emissions 

Modern car engines are designed to be efficient from the moment they are switched on, so revving up like a Formula 1 car in pole position only wastes fuel and increases engine wear. Using your gears wisely by changing up a gear a little earlier can also reduce revs.

6 Idling is wasting fuel 

When the engine is idling, you're wasting fuel. If you're likely to be at a standstill for more than three minutes, simply switch off the engine.

 – Source: Defra UK

Expert answer

The run flat tyre is designed to allow you to drive home safely even if there is a loss of inflation, but a consequence of that would be that you would dispose of the tyre after that and get a new one. The reason for this is that the sidewall is very thick and it is difficult to examine this for damage. Here is what Bridgestone have to say about it on their Run-Flat website:

"It depends on how far and at what speed the car was driven after the puncture was sustained. Repair is possible only if deemed so by the tyre sales store. Preconditions include a puncture of less than 6mm for both side-reinforced type and support-ring type Run-Flat tyres, plus minimal damage to the support ring in case of the latter. However, it is strongly recommended that the tyre is replaced as its durability will have been weakened after being repaired."

A Continental Tyres spokesperson told us, "you should not repair or put back in service self supporting runflat (SSR) tyres that have been damaged or run flat. This is because it is impossible to know what internal damage has been caused to a tyre that has been run on flat."

Obviously this could end up being expensive if you have to get a new tyre every time you get a puncture, but the idea is that if you do have a puncture you can drive home safely and don't have to be left stranded at the side of the road.

Expert answer

Hi Alec,

First, the disclaimer: a huge number of factors will influence your average fuel consumption, including the route you take; whether your tyres are inflated correctly; if you're driving around with a boot full of golf clubs; and of course how you drive.

All that aside, a good rough estimation is to split the official combined and urban economy figures. This varies for every car but I think you should use about 6.0 litres/100km - which is 47mpg in old money.

Let me know if you want a few basic tips on how to improve your economy and how to measure your consumption precisely.

Expert answer

Hi, we have put this question to Bridgestone and we will come back to you with an answer as soon as possible.

Expert answer

Hi Joe,

I recently drove the Golf BlueMotion and the review will go up shortly, but what I can say is that I was really very impressed by the car for a number of reasons. Obviously this is the full BlueMotion version and that differs slightly to the 'BlueMotion Technology' model that we have seen before. 

This new car gets a full raft of eco measures. There is Stop/Start, regenerative braking, a modified radiator grille, low rolling resistance tyres and a specially tuned diesel engine. The result is emissions of 99g/km and fuel economy of 3.4 l/100km. Now, you would want to be really hyper-miling to get those figures but we got close to that on our few days with the car. The economy was really staggering. 

There is 105hp from the 1.6-litre diesel and it isn't a rocket: 0-100km/h takes 11.3 seconds. It is however, a very nice car to drive. It doesn't feel slow because it is geared well. And it is a nice place to be. For the price, it is quite well equipped. 

Obviously, price is an issue. There is no real incentive to buy this car for its emissions like there is in other markets. In some markets, such as the UK, if your car has less than 100g/km you don't pay road tax, but here everything under 120g/km is Band A and the Ford Focus 1.6 D Style will cost you about the same to run, yet is €1,545 cheaper to buy. 

To answer your original question though, if I was buying a Golf, yes this is the one I would have (aside from the GTI of course). I really liked it. 

You also have to look at the Skoda Octavia too. For €23,820 you could have an Octavia with the same engine, but with the DSG automatic transmission. Hope this helps, feel free to come back to us if you have any more questions.

Expert answer

Hi Jerry,

Do you mean you'd like to fit smaller wheels to your car or fit smaller tyres to your existing wheels? The 'R17' part of your tyre size name means they fit 17-inch diameter wheels. You cannot fit R16 tyres to larger wheels.

If that doesn't answer your question please leave a comment in the box below and we'll come back to you again.

Thank you

Expert answer

Hi James,

We'd like to put this one to BMW and a tyre expert. Can you tell me what size tyres you have, the brand they are and whether you have any relevant extras like sports suspension? Just post the details in the comment section below.

Thank you

Expert answer

Hi Ciaran.

Funnily enough, I was just last week at a tyre event and we got a full briefing on tyre wear, which I knew would come in useful somehow.

Firstly, no this isn't normal wear at all unless you were on a track racing. I take it that you aren't and from what you are saying the wear is even. Usually shoulder wear is a sign of under-inflation. Under-inflation can also lead to tyre blow-outs.

Drivers should check their tyre pressure every two weeks according to the manufacturers. One-sided wear is usually an alignment issue and that doesn't seem to be the case here.

Anyway, we contacted Bridgestone / Firestone on your behalf and they are happy to send out an engineer to inspect your tyres. I have sent you their details. They want to check out if there is a fault and we can take it from there.

What we will say about tyres is that it does not make economical sense to buy cheap ones. They tend to be of lower quality and there is no wisdom in having poor tyres on your car. See how you get on with the engineer and let us know by posting a comment back on this page.

Hope that helps.