What a lift shows you
Two-thirds of a car is the side you never see. Everything that holds it together, everything that leaks, and every consequence of ten New Jersey winters lives down there, and all of it is visible in about twenty minutes to anyone standing under it. This is that walk, nose to tail.
The practical question first. You get a car in the air one of two ways: the seller has a lift and will put it up, or you take it to an independent shop for a pre-purchase inspection. Call two shops and ask what they charge and how long they need — prices differ enough by area that a number printed here would only mislead you. Ask specifically for a lift inspection rather than a scan; plenty of places will plug in a code reader and call it one.
One technical thing worth knowing first. A drive-on lift holds the car by its tires, so the suspension stays loaded — fine for the exhaust and underbody, useless for checking play in joints. A frame-contact lift hangs the wheels free, which is what you need to feel a worn ball joint or wheel bearing. If a shop has only one type, ask which, and know which half of this list you are getting.
The front bumper support and radiator core support
Behind the plastic bumper cover there is a steel or aluminum beam, and behind that the structure that carries the radiator. This is the first thing to absorb a front impact and, being invisible, the last thing anyone straightens properly.
Look for a beam that is kinked, welded, or finished differently from the rest of the car's hardware, and for crush cans — the deliberately collapsible sections behind it — that are not the same length side to side. On the core support, look for creases and for welds flatter and shinier than the factory's.
The engine and transmission, from below
From above you see a plastic cover. From below you see the truth: the oil pan, the front and rear main seals, the transmission pan and its seams, the axle seals, and every surface that catches a drip.
Distinguish wet from dirty. Dry, crusted grime is a leak that stopped, or one so slow nobody cares; clean metal with a glistening film is active. A spotless underside on an older car is its own finding — a degreaser resets all of this evidence.
Front suspension
Control arm bushings — rubber, and cracked or separated rubber is visible from three feet away. Ball joints, which get checked by hand with the wheel hanging free. Strut bodies, which should be dry; oil running down a strut means it is finished. Sway bar links and their bushings, which are the cheap cause of most clunks.
Also look at what is new. One brand-new control arm on an otherwise old car is a clue, not a problem: something happened to that corner.
CV boots, axles and the steering rack
Constant-velocity joints are packed with grease and sealed by a pleated rubber boot. A split boot throws grease in an arc across the inside of the wheel arch, and the joint behind it is on a clock from that moment. Boots are cheap; joints are not.
The steering rack has boots at each end too, and the same logic. Wetness at either end of the rack is power steering fluid, and a rack is one of the more expensive things under a car.
Rockers, floor pans and jacking points
Now you are under the middle of the car, which on a unibody is the structure. Press the underside of each sill. Look at the pinch weld where a jack is meant to go: crushed and folded is somebody jacking in the wrong place, rotted is a different and more serious finding.
This is also the best view of the floor pans you will get without pulling carpet. What counts as cosmetic versus structural here is worth reading separately — rust, and where it actually matters sets out the three tiers we use.
Brake and fuel lines
They run the length of the car, which is why this station spans most of the bar. Follow them from the master cylinder to each wheel. Surface rust here is universal; layered, flaking scale is not the same thing, and neither is a section spliced with a compression fitting — a repair some shops will not sign off on at all.
Fuel lines and the tank straps get the same look. A rusted strap is a fuel tank held up by one strap.
Exhaust, catalytic converters and heat shields
From the manifold back. Look for weeping black staining at joints, which is an exhaust leak marking its own location, and for hangers that have rusted through and been replaced with wire. Rattling heat shields are the least important noise a car makes and one of the most common.
Note whether the catalytic converters are present and look original. Aftermarket converters are legal in some configurations and not others, and the requirements are a question for a licensed inspection facility rather than a general article.
Driveshaft, transfer case, differential
On rear- or all-wheel-drive cars there is a shaft running the length of the floor with universal joints at each end and often a support bearing in the middle. Look for a rubber carrier bearing mount that has collapsed, and for fluid weeping from the transfer case or differential seals.
On an all-wheel-drive car, mismatched tire circumference puts the driveline under permanent strain — which makes four mismatched tires a mechanical finding, not a shopping list.
Rear suspension and subframe
Same examination as the front, with two additions. Rear shocks leak quietly for years because the symptom is gradual. And rear subframe mounts are a classic salt-belt corrosion location — look at the metal around the bolt rather than the bolt itself.
The tail: rear structure, spare well, hitch
The rear crash beam and rails get the same reading as the front, and from underneath you can see the outside of the spare well, where water sits and rust starts. A tow hitch is a question rather than a defect: what was towed, how often, and does the history match the answer?
Finally, while the wheels are off the ground and free, this is the moment to look at the inside shoulders of the tires — the edge you cannot see from outside, where an alignment problem writes its evidence. And to take actual brake measurements, which we have set out in reading brake wear.
Why we publish ours
Every car here goes on a lift before the front row, and the findings go on the 168-point sheet we publish in full, unflattering parts included. We would rather you arrive knowing the right rear shock is weeping than find it yourself and wonder what else went unmentioned. And if you want your own mechanic to run this list first, take the car. The answer is always yes.
A general guide to what is visible from underneath a passenger vehicle, not an inspection standard; component layout varies widely by drivetrain and model. Emissions requirements, brake line repair practice and safety-inspection criteria are jurisdiction-specific — confirm them with a licensed inspection facility or the New Jersey Motor Vehicle Commission.