Q How often should car tyre pressures be checked and is it wise to adjust them according to driving conditions? BM from London

A The car’s handling and braking will suffer if tyre pressures are too low, and fuel economy will drop. Readings should be checked when the tyres are cold because they rise as you drive. As all tyres are slightly porous, the pressure slowly decreases, so check them periodically. The pressure figures cited by car makers include optional higher settings for, say, carrying loads.

As forecourt gauges are unreliable, invest in an easy-to-read digital pressure reader such as the Michelin MS-4650 keyring gauge (£10 from www.tyresonline.net , 0845 260 1600).

Q What is the safest and most reliable small car to replace my Toyota Yaris? PB from Dumbarton

A In terms of safety, the easiest way to compare makes and models of cars is to look at a vehicle’s Euro NCAP test scores. Not all cars are tested but those that are receive three scores, each rated out of five.

The first score is for adult-occupant safety, the second for child-occupant safety and the third for pedestrian safety. The newer model of Yaris, introduced in 2005, gained five stars for adult safety, three for child safety and two for pedestrian safety. The safest supermini cars, according to NCAP, are the Peugeot 207 (five, four, three) the Seat Ibiza (five, four, three) and the Mazda2 (five, four, two). See the full list of scores at www.euroncap.com .

As for reliability, it’s difficult to assess it accurately because manufacturers don’t share data about repairs done under warranty. What’s more, the big reliability surveys completed by owners, such as the What Car?/ JD Power customer satisfaction poll, tend to be subjective. Last year’s survey was topped by the Honda Jazz, the Skoda Fabia and then the Yaris for this category of car. The Jazz edges the Skoda for safety with its Euro NCAP score of four, three, three versus four, three, two.

A more objective view of reliability is provided by Warranty Direct, a third-party warranty provider. It rates the Japanese makers highly, with the Yaris taking top spot in the supermini section. Visit www.reliabilityindex.co.uk for more details. If you are still concerned about buying the Yaris, we suggest the Mazda2.

Q My car is being used for target practice by a bird, possibly a wagtail, that keeps returning to the mirror housings. As the car has to be parked outdoors, do you have any ideas for prevention other than baking a wagtail pie? JF, by e-mail

A Bird droppings are bad news for a car’s paintwork. If you don’t rinse the mess off quickly, it may eat into the paintwork or lacquer. This costs Britons £57m per year in repairs, according to a report by Zurich insurance, which advises you to remove bird mess by spraying it with water rather than wiping it, to avoid scratches.

Some birds will catch sight of their reflection and attack a car, thinking it is an enemy bird on their territory. Your rogue wagtail may well be doing this. The answer is to remove the source of its annoyance. Tie a plastic bag over each side mirror: that way, the reflections will disappear and the mirror housings will be protected. The bird will hopefully soon realise his “enemy” has gone, and move on.

Q I’ve always wanted to buy a funky camper van so I can give up my job and head off around Europe. I’m hankering after an old Volkswagen, probably of 1960s or 1970s vintage. Are VW vans as reliable as their reputation suggests or would I be better off with a less sexy Ford Transit conversion? HA from south London

A A vintage camper van is never going to be as reliable as a modern vehicle, but it will be mechanically simpler. If it breaks down it is usually easier to repair and it’s often possible to perform a DIY job. The Transit is unlikely to offer greater reliability although it may be cheaper.

VW campers have cult status and, depending on the exact fit and condition, cost from £5,000 to £15,000. The good news is that resale should be straightforward, parts are plentiful and owners’ clubs are helpful. See www.vwcampers.com, a portal for several clubs that also includes classified ads.

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E-MAIL YOUR QUESTIONS TO carclinic@sunday-times.co.uk . Alternatively, write to Car Clinic, InGear, The Sunday Times, 1 Pennington Street, London E98 1ST. Please supply us with a daytime telephone number, the town or city you live in and as much detail about your car as you can. We regret that we cannot send personal replies or deal with every letter, so please do not send original documents or SAEs. Advice is offered without legal responsibility