Michael McAleer answers your queries
From Dave Maguire, Ballymount, Dublin 12:
Just recently I bought a brand new Audi A3 but I'm having a hard time getting a nice set of alloy wheels for it.
Seemingly on the new A3 - and I also believe on the new VW Golf - the manufacturers have changed the off-set of the studs and none or very few alloy companies have anything made to fit these cars. Hopefully you may know different.
By no means am I a boy racer. I just like to have my car smart looking and nice alloys are the car's finishing touch.
Audi and most of the Volkswagen-owned brands are using an offset of 5 in 112. This, for the lay person means a five nut wheel with 112 mm between nuts. Most other mainstream firms use a setting of 5 in 100 mm.
What you have here is a move by the manufacturer to get you to buy wheels only from them. Of course, they are always wary of people using wheels from different manufacturers on their cars.
VW is not the only firm to try this. Most of the premium end car firms do it as well - BMW, Mercedes and the rest. The German execs would have palpitations at the sight of a 7-series running on a set of Mercedes alloys.
However, help is at hand. According to Derek Staunton of Motorway Accessories in Blanchardstown, Dublin, several independent wheel manufacturers supply alloys for these marques.
"These firms would have got the wheel specifications six months before the car's production," he says. He suggests you look at alloys from a firm called Fox Racing, which does RS wheels for the new Audi A3.
Certainly the efforts of manufacturers to end uniformity in the industry seems to be stymied by the wheel manufacturers.
From Aidan Walsh:
You state (June 2nd) that "unless your car is a high performance model . . . converting (the engine) to unleaded (fuel) is probably a false economy".
I have a 1978 Ferrari 308 GTB. Any suggestions? Does Shell's new V-Power petrol offer any hope?
According to a quick trawl of relevant websites (there's a vast library of information on this and other classic car issues on the web), early Ferrari 308s run fine on unleaded but not when they are taking part in high speed or track use.
The problem with today's unleaded petrol is its low octane rating of 95. High performance cars run a higher compression ratio, so the higher the octane rating the better. Super unleaded is 98 octane so that's probably a bit better.
You don't say whether you are using a lead substitute or valve seat lubricant but, if your Ferrari is in good condition and has low mileage, our colleague John Cradden suggests you consider an unleaded conversion, which involves fitting hardened valve seats.
It may also be that some Ferraris may require only re-tuning to cope with unleaded.
If you can live with it and the engine runs happily on unleaded at the moment, you could continue running it until the engine needs a rebuild. Then do the conversion at the same time.
Research by the Vintage European Automobile club says that older high-mileage, correctly maintained Ferraris will have fully settled valve seats, so regression will not be a major factor.
The factory can supply hardened valve seats or in certain cases, replacement cylinder heads already fitted with them.
As for Shell's V-Power unleaded, its octane rating is 95 - like the others. So it's probably no better than any other brand, even if it has been developed in assocation with Ferrari, according to the fuel firm's website.
From Jim Doherty:
I'm getting married next January and, being a complete Mercedes classic nut, I'm looking or I should say I'm hoping to have a Mercedes 600 Pullman limo as the wedding car but I'm hitting a brick wall in finding one.
We have made several phone calls but nobody seems to have come up with a positive response to your query. So, if anyone can help Mr Doherty on his big day, we'd be happy to pass on the details.
• Send your queries to Motors Help Desk, The Irish Times, Fleet Street, Dublin 2 - or e-mail them to motorshelp@irish-times.ie