When looking to purchase a car, most people rush straight to the test drive, not realising that most mechanical faults can be repaired for under $1000, whereas $1000 goes nowhere if the body, paint or interior needs major work. The lesson here is to check the whole car closely before you turn the key.

CHECK COMPLIANCE PLATE
First, and most important, check the compliance plate. Is it missing? If so, why? Do the numbers and dates line up with other identification plates and stampings on the car? Do they line up with what appears on the registration certificate? Do they line up with what appears in the owner's manual and other documentation?Does it support the vendor's story? Is there a big gap between date of first registration and the compliance date? Has the compliance plate been tampered with? Has the panel that it is attached to been tampered with? Dodgy sellers can cut out the whole panel and weld it back into another car to avoid disturbing the compliance plate.

HOW TO TELL IF THE SPEEDO HAS BEEN TAMPERED WITH
Is the mileage genuine? Crooked sellers will wind back the odometer in the instrument panel, or even replace the whole instrument cluster with a lower reading from a wreck, for the simple reason that buyers will pay more for cars with lower mileage.

• Is the mileage consistent with the vehicle documentation?
  
• Are the numbers on the odometer scratched, misaligned, or even painted over?
  
• Are there scratches or other indicators around the dash that the instrument panel has been accessed or replaced?
  
• Are there signs of excessive wear -- heavily worn interior, pedal rubbers, worn seat belts and buckles, worn armrests and controls, a shiny steering wheel and gear-lever knob? Are these parts too new compared to those around them? Does the driver's door or seat sag?
  
• Are there signs of excessive paint chipping around the front of the car and driver's door, scratches under the door handles, even chips that have been touched up? Check the boot and spare wheel as these are often overlooked.
  
• Has the suspension sagged?
  
• Have there been an excessive number of owners? Check the service books and receipts -- these can be conveniently lost on cars that have been "whizzed".

LOOK FOR RUST, SUN DAMAGE AND BAD REPAIRS
Serious rust looks innocuous at first (just little blisters on the paint surface) but it may be in the structure. Such cases get bad quickly and are expensive to fix. Check for water leaks in all sections of the car. Today, there's no need to buy a rusty car.

Look for differences in paint finish and colour. Look for poor alignment between panels and styling lines. Check gaps between panels for consistency. Look for spanner marks on panel and door bolts. Repairs using cheap imitation panels that rust and don't have the required strength can ruin a car.

Cheap imitation headlights cut costs but they can be dangerously out of focus or they can leak, melt or fade and cost hundreds of dollars to replace with the genuine items. Some imitation tail lights can fill with water and generate boot leaks and quickly fade when exposed to the sun. Expensive paint, trim and plastic parts exposed to the harsh Australian sun can also be ruined.

LOOK FOR OIL AND FLUID LEAKS
Oil on the road or drive mean leaks, which are usually expensive to fix. The cleanliness of all fluids can tell you how well a car has been maintained. The engine oil might be clean but look inside the oil filler cap -- does the inside of the engine look clean?

CHECK, CHECK AND CHECK AGAIN!
In addition to the checks you can carry out yourself, if you are serious about purchasing the car consider a professional pre-purchase inspection. Whoever you choose, make sure their first loyalty is to you, not the vendor, which means you choose the tester and pay for it yourself.

State motoring organisation offer pre-purchase inspections. State automotive trade bodies such as the VACC or MTA also offer tests. Independent testers who are qualified mechanics and panel beaters can be very good, because they quickly get to know the shonky operators, and may even save you the cost of a test.

A trusted local mechanic or a specialist service centre that knows exactly what goes wrong with that model and knows how it left the factory can be particularly helpful for an unusual model. Even if a used car comes with a list of faults, it could still be a good buy if an expert can tell you how much it will cost to rectify and the selling price is right. If you are particularly concerned about crash history, a good panel beater should have the equipment to pick the extent of almost any repair.

Each state registration authority should have a vehicles securities register which will tell you if the car is under a financial contract that has to be paid out before it can be sold. Check with the wreck register in case the vehicle was written off and repaired. Collect as many identification numbers as you can including the VIN ready for each call.

Because of privacy laws, state registration authorities cannot divulge ownership details but they may be able to tell you whether what you have been told is consistent with the information they have in front of them. This is a vital check but you must collect the information first during the inspection of the vehicle.

NEW TECHNOLOGY TRAPS
Vehicle component design has changed dramatically over as new emissions, fuel efficiency, anti-theft and safety requirements have dictated new solutions. In an increasing number of cases this technology is geared to making the new car buyer's term easier and almost maintenance-free but ready to catch up with the next owner. As today's cars get older, they can generate unexpected expense:

Remote Central Locking
To replace a lost or stolen keypad (or indeed key) can cost anything up to $2000, especially if the vehicle's body computer has to be reprogrammed by the manufacturer to a new key pad. A generic cut ignition key on its own is no longer enough when the vehicle's security system relies on an ever changing set of codes generated by a remote transponder programmed to communicate with your car, and your car only. Even if the spare remote is missing, check on the replacement cost before agreeing to a final price.

Catalytic Converters
These are now a routine service item in the vehicle's exhaust system that can cost several hundred or several thousand dollars depending on the car. Some shonky sellers are replacing them with empty cannisters or a length of pipe. 

Electric Power Steering
In an increasing number of cars, this new technology can generate an engine-out repair to fix a simple steering fault.

Ignition Coil Packs/Integrated Ignition
Intermittent engine faults such as difficult starting, engine miss or rough running can generate a chase-your-tail replacement of expensive coil packs and distributors with integrated ignition modules and other items that can cost thousands until the fault is isolated. On some new cars, if the distributor's oil seal fails, engine oil can drown the electronics inside.

Fuel Injectors and sensors
A combination of poor quality fuel, running on empty and faulty sensors can cause these expensive items to clog and stop injecting fuel altogether or dribble it out when they are supposed to spray. If an injector clean doesn't work, allow thousands for replacement depending on the number of cylinders. A strong smell of petrol under the bonnet can indicate injector seal failure for similar cost.

The oxygen sensor which is a probe in the vehicle's exhaust is an ongoing maintenance item for optimum performance and economy. The crank angle sensor can die from ongoing engine heat and can also require routine replacement.

High-Pressure Electric Fuel Pumps
All modern engines rely on at least one, sometimes two, high-pressure electric fuel pumps -- one of which usually lives in the fuel tank which can generate access problems with some models.

These expensive pumps hate water and dirt, which is why they often fail not long after someone has run out of fuel or if the fuel is dodgy. They also rely on the fuel tank's contents to keep them cool so repeatedly driving on less than a quarter tank in hot conditions can shorten their life. If you can hear the whirring of a fuel pump inside a car, it usually means it's on its way out.

Four Wheel Alignments
Today's rear suspensions are often more sophisticated than the front, which means they can be knocked out of alignment just as easily by backing into a kerb or hitting a pothole. Old style two-wheel alignments and their machinery are next to useless on most new cars when all four wheels need to be squared and aligned together. Check for uneven tyre wear on all wheels and steering or handling that doesn't feel right.

Sealed Suspension Struts and Bushes
For ease of manufacture, more cars are being fitted with shock absorbers/dampers and bushes built into the suspension components. This means that a once simple $100 shock absorber or bush replacement can cost $500 or more for the whole suspension item.

Hydraulic Engine Mounts
To dampen engine vibration, more cars feature engine mounts filled with hydraulic fluid which can leak out over time. On today's front-drive models, the extra movement can cause expensive exhaust systems to snap so they are a vital check item.

Timing belt/water pump
Most cheaper cars rely on a toothed rubber belt to drive the camshaft(s) which must be replaced at the set interval (usually 100,000km or less) or you risk big engine damage. It is now more common to use this belt to drive the water pump which requires the same labour to access. Prudent mechanics suggest the replacement of the belt, water pump, belt tensioner and thermostat at the same time when replacement of any of these items individually requires the same labour bill.

Antilock Brake Computers
There is no doubt that antilock brakes are a wonderful advance but the ongoing computer failures especially in some European models can generate a $1000 repair bill. Check first if there is a local specialist who can repair them. On some repaired wrecks, the antilock badges might be there but the whole system might be missing if the donor repair vehicle was a cheaper model.

ECU (Electronic Control Unit)
This is the computer that controls the engine and sometimes the automatic transmission. It can also be the heart of the vehicle's security system and this is where the cost can go ballistic. On some vehicles, these computers shut down never to work again if removed or tampered with which makes secondhand ones useless and can lock owners into brand new replacements and factory re-programming.

Headlights
Most people know that the new Xenon technology brings big replacement costs but even the cheaper headlights which are moving to plastic lens covers (instead of glass) have hidden costs as well. Theoretically better for resisting stone damage, these plastic covers craze over time with gravel rash and Australia's UV levels are now turning the older ones opaque. Some can be polished clear but also check to see if the cover can be replaced separately or whether the whole headlight has to be replaced at a cost which in some cases can approach $1000.

Plastic Radiators and Thermostat housings
Modern radiators usually have aluminium cores attached to plastic tanks with rubber seals at each end. As the plastic tanks crack, or the seals fail, they can be repaired at least once but after that the aluminium tags that crimp around each end can break off dictating a brand new radiator at considerable cost. Plastic thermostat housings and the thermostat inside can cause engine failure when they crack or fail so on some cars they have become a critical preventative maintenance item.

Air-conditioning electronics
Once controlled by a simple solenoid, today's aircon systems can trigger a range of functions in the car's computer systems to maintain engine power and cooling as soon as it's switched on. If a vehicle stalls as soon as you switch the air-conditioning on or the cooling fans don't cut in, locating exactly which electronic module or circuit is at fault can be an exhaustive process especially with some of the latest European cars.

Wipers
Today's wipers don't look anything like they used to. Factory wiper blades and the pantograph sections that support them are one of the most carefully engineered parts in a car yet too many dealers and service centres are throwing these expensive parts in the bin and substituting them with nasty throwaway plastic items. These often don't fit and can fall apart -- leaving a large exposed retaining clip to carve a groove in the windscreen. Allow up to $200 for replacement depending on how much of the original assembly is missing or damaged.

Heating and Ventilation Controls
The old way was to use a system of slides, levers and cables to change the settings of the heating and ventilation system. Although they are starting to fail on older cars, they can be repaired.

Today's cars rely on a series of buttons or twist controls to activate a system of vacuum switches that involves lots of hoses and plastic vacuum reservoirs that can crack or leak. They can be extremely fiddly to access behind the dash and you can't always get replacement parts -- even on popular models. This means that you need to check every function of the heater-demister system, with the aircon on and off.

Aircon cycling
Like a domestic refrigerator, the air-conditioning compressor should switch itself on and off automatically after you turn it on. This compressor cycling is controlled by a pressure switch. These switches are usually unique to each model and they are getting harder to source for many cars over five years.

Switch the air-conditioning on with the engine running and check under the bonnet that the compressor clicks in and out in reasonable time intervals. A nasty trick is to bypass a faulty switch so it works for the inspection but blows up the whole system later. Check that the thermo-electric fan also kicks in and out and the temperature gauge doesn't rise excessively with the air-conditioning on.

More new cars are featuring climate control with a computer that controls the exact amount of heat or cooling to maintain a preset temperature. These computers are now failing and can be hard to check.

All-Wheel-Drive Systems
More soft roaders use clutch packs to transfer drive to the rear wheels when traction is lost. These clutches wear out just like any other clutch with use and can cost big dollars to replace.

Bonded Trim
This is a nasty development where the cloth or trim is bonded to the seat padding or sponge backing -- ready to delaminate in the Aussie heat. Because the seat trim is not separate, often the whole seat has to be replaced. Cloth headlining can also separate from its backing and fall down which is also labour intensive to replace. Some trimmers may have a cheaper solution depending on the vehicle but don't overlook any signs of bubbles or wrinkles in the trim.

Windscreens
An increasing number of windscreens have special heat reducing surfaces, ceramic trim, heads-up display panels and self-regulating wiper controls that lock owners into imported factory replacements. Don't shrug off all windscreen replacements as a sub-$300 item without checking.

Airbags
These have become a theft item and are also often missing in backyard repairs. Check that the warning light still lights-up at start-up, then disappears.

Aluminium/plastic sumps
These items used to be made of pressed steel which would bend or yield on impact. Now most new cars have cast aluminium sumps (or oil pans) on engines and transmissions or in some cases, plastic. On high-crowned Aussie roads, even small stones can shatter or crack these items. Unscrupulous repairers recycle them using a fine clear bead of sealant to hide the crack and oil leak.

Extended Oil Changes
Yes, oil and filter technology has improved radically for longer service intervals, but the engine oil is also the modern car's pollution trap. Most owners don't take any notice of the time requirements in their service books or the extra services required for short, stop-start running which means that many city cars are sludging themselves to death. Once sludge blocks the engine's oil ways, the engine in some models has to be thrown away.

Original article by Joe Kenwright, updated 2009 by the Carsales Network

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