Fuel to the fire

A spokesperson for the AA says: ''If your primary use is likely to be short, suburban runs, the diesel is favourite as it works more efficiently and economically. If your driving is largely urban (where the catalyst is needed) or on motorways, where the differences in economy between the two are least, a petrol engine may be better.

''With regard to emissions, the petrol engine is cleaner than it ever was. With catalyst fully operational, the toxic exhaust emissions are one-tenth of what they were 10 years back. But it can take a couple of miles for the catalyst to heat up, and in that time emissions can be quite considerable - a problem the diesel does not have.''

I have been charged with dangerous driving for doing 109mph on a quiet motorway. The road conditions were excellent and the police advised that their only concern was my speed. Can I be prosecuted for dangerous driving and what will the likely sentence be?

Greg Sanders, a solicitor with Levy & McRae, says: ''When speeds are well in excess of the prescribed speed limit it is quite normal for a charge of dangerous driving to be libelled.

''The test applied by the courts will be to assess the quality of your driving applying an objective test. While excellent road conditions and a light volume of traffic may assist you, the court will have regard to potential hazards such as vehicles pulling into the outside lane when they could not have reasonably anticipated a car approaching from behind at such a high speed.

''A lot will depend on the particular facts and circumstances of your case, the layout of the road for example. If you are convicted you will be disqualified from driving for at least one year and will be ordered to re-sit your test. A substantial fine may well be imposed as well.

''It is also open to the court to find you guilty of a lesser charge of careless driving, although this too may well result in a period of disqualification.''

I have seen a lot of comments in the press recently about the use of mobile phones. When can I use them while driving?

Steven Shepley is the regional co-ordinator for the Institute of Advanced Motorists in Scotland: ''The short answer is never. The law demands that you are in control of your vehicle at all times and has successfully argued that you cannot do that with a mobile phone stuck to your ear.

''Hands-free kits allow you to keep both hands on the wheel, but do not allow you to keep all your concentration on your driving.

''If you need to make a phone call, pull in somewhere safe and do it. If it rings while you are driving then pull in before you answer it. The IAM currently has a campaign, ''Don't talk and drive'' - good advice.

IS gas the answer to cheap, environmentally friendly motoring?

The AA says: ''There are two gas fuels used for cars, liquid petroleum gas, known as LPG, and compressed natural gas, CNG. At present there are only eight or 10 filling points where you can get CNG. LPG is widely used around Europe.

''LPG can cost between 30p and 45p per litre. Our findings have been that fairly high mileages on gas (around 20,000 or more) can be needed to show a cost saving.

''Compared with the engine running on petrol, the exhaust of the car on LPG will contain about 10% less carbon dioxide. The toxic emissions will not be significantly different from a catalyst equipped petrol engine.

''Compared with a diesel engine, an LPG fuelled car will produce significantly less smoke particles and nitrogen oxides; the emissions of carbon dioxide may be similar or slightly greater.''

I was involved in an accident last week near to my friend's house who lives in a rural area. Foolishly, I consumed three large whiskies in rapid succession while waiting for the police to arrive. I was subsequently breathalysed and found to be more than the legal limit. Do I have a defence?

Greg Sanders says: ''In certain circumstances a defence of post-accident drinking can succeed regardless of how foolish you have been. First, the court would have to believe your evidence to the effect that you consumed alcohol after the accident and that this can account for your reading being more than the limit.

''While the courts are not quite so strict about having evidence of you having consumed a 'definite and ascertainable amount' as they used to be, it would certainly assist your case if a forensic scientist can reconcile what you claim to have consumed, and when, with the subsequent readings obtained by the police.''

I was in America last month and noticed many cars had radar detectors fitted. Can I buy one here and are they legal to use?

Steven Shepley says: ''Yes you can buy them here and in 1998 a High Court judge ruled that they are legal to use. The ones currently on the market will detect a Gatso camera in sufficient time for you to react, but probably not a lasar device.

''Also, they do not detect the hand held Vascar units currently used by most police forces, forward facing cameras and those new ones that measure your speed over a distance between two cameras.

''At #300 some drivers think they are a good investment but consider how much better it would be not to be speeding in the first place.''

I recently heard of someone dying after their car plunged into water. What should you do if this happens?

The AA says: ''A car plunging into water might sound like a freak incident, but in 1997 there were 16 deaths in Great Britain as a result of drowning in vehicles compared with 35 deaths from boating

accidents.

''After hitting the water, the car will float for a few seconds and during this time you should attempt to get out as quickly as possible. Open a window before the water level reaches the bottom of the window. If the car is fitted with an opening sunroof this can provide a further means of escape.

''Free yourself and all your passengers from seatbelts and child safety harnesses and escape through the open window or sunroof as quickly as possible.''

Does a failure to comply with the provisions of the Highway Code automatically mean that an offence has been committed?

Greg Sanders says: ''A failure to comply with a particular rule in the Highway Code may tend to establish liability for certain offences such as careless driving, but a violation does not necessarily mean that an offence has been committed. A court is nevertheless entitled to have regard to the provisions of the Highway Code in reaching a verdict.''

The Government has been pressing us to leave our cars at home and cycle to work. I have been doing that for most of the summer, but find the cars pass frighteningly close. Is there anything I can do other than ride on the pavement?

Steven Shepley says: ''Cycling on the pavement is an offence unless there is a dedicated cycle lane, so beware. Despite it being the safest place for you, pavements are for pedestrians.

''Many cities and towns have dedicated cycle routes or cycle lanes on the roadside and you should use these whenever possible. Try and find a quieter route to work or use flexitime advantages.

''If this is not possible then make sure you wear bright clothing, be positive about your riding, but not a dead hero.''

n If you have questions, on legal, technical or safety matters, e-mail them to: supplements@theherald.co.uk