Michael McAleeranswers your questions
From D Brady:
We are considering changing our Opel Vectra but I have seen reports in your paper that a new model is on the drawing board. Is this just speculation and if there is a new model, when will it be introduced?
While car firms are loath to confirm anything about new arrivals while they have current models in stock, we can reassure you that a new Vectra is due for launch here by the end of next year. Reports suggest it will be introduced in the autumn of next year and the word is that Opel is going to drop the Vectra name as well.
Several years ago it introduced the Insignia concept, which at the time was thought to be some form of flagship model, with the brand returning to an Omega-sized car. However, that plan has been shelved and it's likely the Insignia name will feature on the Vectra replacement instead.
While the concept car shown at the Geneva show last month was very much a coupé, the new car will retain much of the front-end look and our colleagues, who recently spotted the new car being secretly tested, say that it also has a far more sloping roof line as well, keeping with the coupé look.
Given that a realistic Irish launch is over 20 months away, if you were to opt for the current generation, the most significant depreciation on the new car will already have occurred and there will also be a used market for the older generation.
The timespan would suggest that it's not really worth waiting that long. By the time you come to change again, the Insignia will be here and you will have the chance to test it.
From L Walsh:
If I change my wheels from the standard 16" alloys to 18" ones, will this have any impact on the accuracy of my speedometer or mileage clock?
A colleague recently told me that it could affect my speed by as much as 5mph (I've an old style speedometer). Is that true?
Both wheel size and tyre size have an impact on the speedometer readings. In most cars the speed is calculated by measuring the turns per mile but the basis for this is that you are running on a standard set of tyres and wheels.
The speedometer is generally set on the standard wheel and tyre fitted to the car so every time you change the diameters of these, your speedometer will be slightly out. In turn, the faster the speed, the larger is the discrepancy. There are various websites that allow you to input your new wheel or tyre dimensions and compare against the standard size.
They then calculate the different readings you will get at various speeds. All other things being equal and running on a 165mm tyre with a 55 per cent sidewall, if you change the wheels from 16" to 18" for example it will give you a 10km/h difference at 120km/h. That's certainly enough to incur some points.
We used one of the websites (http://www.paspeedo.com/calculator.htm) but there are many others online that perform similar calculations.
Sadly, all this is not going to act as grounds for dismissal in court, as it is the responsibility of the motorist to ensure that their speedometer is properly calibrated.
From R Lavelle:
I have a 2004 Suzuki Grand Vitara 2-litre diesel. It's getting nothing like the stated fuel consumption figures. Is this normal, and what can I do to improve the fuel economy?
Drivers rarely achieve the official fuel consumption figures. These figures are to be used as a guide rather than a stated fact. The situations under which they are established are a long way off the average Irish driving conditions.
They do serve a purpose however: they illustrate the difference between rival models in fixed conditions and as such you can expect similar differences in normal driving.
There are, however, ways you can improve your fuel efficiency. Here is a short list of tips:
Slow down - driving at the speed limit can make a significant difference.
Check tyre pressures regularly - keeping tyres properly inflated will help improve consumption.
Avoid abrupt acceleration.
Keep your car properly maintained - blocked air filters, dirty oil and lack of attention to other maintenance items all reduce economy.
Cut back on air conditioning - Most air conditioning compressors run off of pulleys attached to the motor. This creates drag, which makes the engine work harder.
At low speeds, roll down your windows and enjoy some fresh air (at motorway speeds open windows create even more drag than air conditioning does).
Send your queries to Motors Helpdesk, The Irish Times, Tara St, Dublin 2, or e-mail motorshelp@irish-times.ie