How to test drive a car so it tells you something

A test drive cannot tell you what a car will cost over five years, how much of your money it will hand back when you sell it, or whether it is the right shape for the life you lead. None of that is visible from the driving seat. You work it out sitting down, with numbers, before you go near a forecourt.

So arrive with the decision mostly made. Narrow the field with the finder , settle the money with depreciation explained and what a car costs to run , then drive the two or three cars that survive — looking, deliberately, for reasons to say no.

• Book at least 45 minutes, and say on the phone that you want a motorway and a bad road. A dealer who cannot arrange either is telling you something before you leave the house.
• Ask for the car cold. One warmed up in the car park hides the cold idle, the first-minute gearbox behaviour and, on a hybrid, how long the engine runs before the battery takes over.
• Ask whether the demonstrator is the specification you would order, and specifically which wheels and tyres it has. The same car on 19-inch wheels and on 17s rides differently and costs differently to run.
• Bring your things. The pushchair, the child seats, the dog crate, the cello, the biggest thing you routinely carry. Not a tape measure — the actual object.
• Bring whoever else will drive it, and your licence. Two adults who both need the seat in the right place is a harder problem than one, and better discovered now than in the delivery week.
• Drive your shortlist back to back on the same day if you can. Memory for ride quality is short, and generous to whatever you drove last.

Do these in order. The first one is not a formality — it is the test most likely to end the visit early, and it costs nothing to run.

1. 1

   Set the driving position before you move

   Seat height first, then distance from the pedals, then the backrest, then the wheel — in and out as well as up and down. You are looking for square shoulders, a slight bend at the elbow and knees that do not foul the wheel. If you cannot get there, stop. No other quality of the car compensates for a position you fight for the next five years.

2. 2

   Sit still for two minutes

   Set the mirrors. Look over your shoulder and find the blind spot. Check what the windscreen pillar hides when you turn into a junction. Then find the wipers, the demist and the hazards without looking. A cabin you cannot operate blind is one you will operate badly in the rain.

3. 3

   Pull away cold, with the radio off

   The first thirty seconds are the most informative of the whole drive. Listen for a cold rattle, a gearbox that hesitates before it engages, an electric whine that changes pitch. Leave the radio off for at least the first ten minutes; a good stereo has sold a lot of noisy cars.

4. 4

   Do a hill start and a real merge

   Find a gradient and stop on it, then pull away. Then take a motorway slip road at the pace you would use in traffic. Acceleration in this catalogue spans 5.0 to 14.9 seconds to 100 km/h with a median of 8.6, and the difference between the ends of that range is how big a gap you need in a line of lorries. That is a safety judgement you should make from the seat, not from a number.

5. 5

   Find the worst road you can

   Speed bumps, a broken road edge, a level crossing — whatever the worst surface on your normal route resembles. Ride quality is where wheel size shows up, and it is the one characteristic you will notice every day for years. Do it at 30 km/h and again at 50.

6. 6

   Get to motorway speed and stop talking

   At a steady 120 km/h, listen for wind noise off the mirrors and screen, and for tyre roar that rises and falls as the surface changes. Notice how much small correction the steering asks for. Notice whether the seat is still comfortable now that you have been in it half an hour.

7. 7

   Brake hard, once, from speed

   Somewhere safe, with nothing behind you, and warn your passenger. Check for judder through the pedal, any pull to one side, and how far the nose dives. On a hybrid or electric car, feel the handover from regenerative braking to the friction brakes — a clumsy one cannot be unfelt.

8. 8

   Turn the driver assistance off, then on again

   Lane keeping, speed warnings, whatever tugs at the wheel or chimes. Find out how many presses it takes, whether it can be done while moving, and — the important one — whether it stays off next time you start the car. Some systems reset every trip, and that is a daily annoyance you are buying.

Everything above happens while the car is moving, which is the part dealers are set up for. These decide most purchases, and nobody will suggest them.

• Park it in a space the size of yours. Lengths here run from 3,595 mm to 5,018 mm — a spread of over 1.4 metres. Measure your bay or garage first, then reverse into a space that size: once on the camera, once ignoring the screen.
• Load the boot with your own things, parcel shelf in place. Boots here run from 130 to 1,844 litres, median 451 — but litres are measured by pouring blocks into a shape, and a square 400-litre boot with a low lip beats an awkward 451. How much boot do you need covers what the number hides.
• Fit the child seats. Actually fit them, rear-facing if that is what you use, in the position you would use. Then sit in the front seat in front of one and see whether your legs still fit.
• Stay in the seat for forty minutes, not ten. Seat problems appear between minute twenty and minute forty: thigh support that stops short, a lumbar shape that does not match yours, nowhere comfortable for your left foot, an armrest at the wrong height.
• Sit in the back, behind your own driving position. It is the only honest way to measure the space.
• If it is electric, walk the cable. Which side is the port on, how far from the front, and does your home cable reach it from where you actually park? Charging explained has the rest of that homework.

• A rattle from the trim on a rough road at low speed. Rattles do not improve with age, and chasing one is miserable.
• Wind noise that rises sharply above about 100 km/h. It usually comes from the mirrors or door seals and it is effectively permanent.
• Tyre roar that changes when the surface changes. That one is the tyres rather than the car, and tyres are the cheapest thing on a car to change.
• An automatic gearbox that hunts between ratios on a gradient, or a stop-start system that restarts with a shudder.
• Steering that feels vague at motorway speed and wants constant small corrections. Forty minutes of that is tiring; forty thousand kilometres of it is a reason to sell.
• Anything you notice twice. On a test drive you are at your most forgiving. If it registers now, it will register every day.

• Is this exactly the specification, wheels and tyres I would be buying? If not, what is different, and can I drive one that is?
• What are the service intervals, and what does a service cost at this dealer?
• What tyre size is fitted, and what does a full set cost? It is a running-cost line you can find out in one phone call.
• Can I have the car overnight? A twenty-four-hour loan answers the parking, loading and cold-start questions at once.
• What is the trade-in figure for my current car, in writing, before we discuss the price of this one? Keeping the two negotiations separate is worth money.
• If it is used: where is the service history, when are the cambelt and brake fluid next due, and can an independent inspection be arranged before I commit?

The first answer matters most. A brilliant drive in a car you cannot order is worth nothing, and a demonstrator on smaller wheels than the car you would buy is a different car in the way you notice daily.

If two cars both survive all of this, the tie-break is not the drive. It is the five-year total — go back to what a car costs to run and let the arithmetic finish the job the test drive started.