For those who do not have a mechanically-minded friend to shop around with, here are some useful tips:
History: Ask the owner for the service logbook and about past owners and accidents. Check that all major services were fully completed. If comparing a car that is close to or overdue for a major service with one that just had one, the latter is better value.
Kilometres: A car that does much less than the average of 20,000 km per year will be less worn and thus worth more. Ask whether it was used more on the highway or around the city (which wears on gears, brakes, engine).
Exterior: Get the car in a well-lit, unshaded place to look closely for scratches, dints and colour inconsistencies. Check all panels line up, and door trims and bumpers are fully attached. You might be able to live with a few dints, but unmatched panels and colour tints are evidence of a major crash. A different tinted panel that still has signs of damage shows the work was not done by an insurer-approved repairer. Check around a towbar for corrosion and rust that saltwater may have caused.
Interior: Look for frayed fibres, tears, holes and burns in the seat belts, carpet, door trims, and under seat covers. Has the ash tray been used? Check the operation of the seat belt pull-tension, belt buckles, seat reclining and movement, and the child door locks. Wind windows up and down, checking for noisy motors. Try the interior and exterior lights and the wiper blades.
On the test drive: Turn off distractions to listen for banging or knocking, especially while accelerating, turning or braking.
After checking the park brake, check for the following in the foot brake:
1) Persistent high-pitched screeching (when brake rotors are dry, non-rusted) means pads need replacing;
2) If braking feels under-responsive, fades or pedal 'sinks' there may be a fluid leak or air bubble in the brake line;
3) If wheel pulls to the side under braking there is uneven wearing of the brake lining or containment in brake fluid.
4) Loud metallic grinding or growling means brake-pads are worn away and brake rotors will need re-skimming.
5) Vibration or pulsating (when not under heavy anti-lock braking) indicates warped brake rotors or tyres out of alignment.
Look for exhaust smoke under acceleration while parked or pulling away from traffic lights. Front wheel drive cars may have torn CV boots, thus exposing the drive shafts to damaging grit. These shafts are damaged if you hear knocking or clunking when slightly accelerating in a tight circle in a carpark.
Roadworthiness: You can arrange for a pre-purchase vehicle inspection through your state's royal automotive club, a private inspection company, or even your local mechanic.
If you want to inspect it yourself, be prepared for some work. Pop the front hood to check the engine bay for oil leaks and for correct power steering and brake fluid levels (this is marked on the side of the container). If the brake fluid appears murky, it needs replacing.
Next, check the brake pads and shoes, and the tires for bubbles, cuts and proper tread depth. Illegal depth is below 1.5 mm anywhere in contact with road. Note that the manufacturer's wear bar (often marked "TWI") is for optimal performance and may be above 1.5mm. Also, look closely for cracks in the suspension bushes, as well as oil leaking from shockers.
Finally, check the exhaust pipe for holes and cracks (i.e. a black carbon stain), and while you're underneath look for oil leaking from the engine, steering rack and transmission. •