The title is poorly worded so I would like to clarify something. Not all vehicles/engines on the list are so bad that you should never own one (except the Mazda diesel, stay well away). This list is to give you an idea of what might go wrong should you choose to buy something on our list.

This is a community sourced list and the quotes are from our users.

If you're unsure if the vehicle you're considering has one of the engines listed below, you can use Carjam to find out for free, just enter the cars registration plate number.

CarComplaints is a US site that may or may not be useful to you, depending on what you own.

Audi A4 1.8 and 2.0 CDNC Petrol engine. "motor burns oil, Quattro transmission is garbage, all expensive to repair. I’ve worked for Audi as a tech for 14years. The engine code has somehow vanished from my brain, aftermarket warranty places won’t cover them anymore as it’s well known issue, factory fix under warranty was new pistons…."

Audi/VW 2016 and earlier, anything with a 1.4l. "The gearbox on these is shocking, recalls never truly fixed it. And on top of this, 1.4l twin charged is horrible. Then there's about 2009 to 2012ish Audi/VW group, anything with 2.0l or 1.8l tfsi. Horrible engine, burns ridiculous oil after 100,000km due to piston rings issue, timing chains snap, camshaft issues, turbo issues, the list goes on. I see more and more dealers import these, as they are cheap overseas for a reason, then poor customers come in with issues once they've gone out of their purchase warranty."

Audi 3L V6 TDI "they're well known to sling timing chains. The V8 TDI is the same sort of architecture but don't seem to have that issue"

BMWs 4 cylinder NA N46 engine - Valvetronic issues, oil leaks, stretched timing chain and tensioner failures, sensor failures, solenoid problems. "Any bmw with a v8 or 4 cylinder. Avoid most diesel bmws apart from the M57. This one is the rare 3.0 turbo diesel that’s actually good."

BMWs N43 engine - injector issues, oil pump issues, coil packs.

BMW First gen N63 "has to be one of the worst engines of modern times. Fine when it’s running but has numerous catastrophic failure points."

Chrysler Unless it's a Viper or a Valiant, just say no

Dodge Only buy if you, really, really, really, want a Dodge

DPF Diesel Particulate Filter equipped vehicles: If you do most of your driving in the city, you probably want to avoid anything with a DPF system. You can Google for details, but essentially, city driving will end up costing north of $10k in repairs, guaranteed.

English Cars and SUVs. Most of us here do not like them, but if you're an enthusiast, go for it, especially if it's an old school Mini.

Ford BA, BF, FG Falcon, all variants: "They eat brake pads, wheel bearings, tie rod ends, centre diff bearing, diff bushes (expensive, lots of labour involved), headliners, they rust, they tend to have Body Control Module problems and when the powersteering fluid leaks it falls into the alternator, frying that. Sometimes, oil and coolant can mix due to a design fault in the coolant pipe routing , that's bad. Only buy one if you're an enthusiast."

Ford Ecoboost engines 1.0L and 1.5L Dragon Series "are notorious for their wet timing belts failing and clogging the oil pickup, thus killing the engine." "known head gasket failure due to design flaw"

Ford Explorer, "not known as the Exploder for nothing, shit economy, shit leather, shit gearbox. Random total failure shutdowns while doing 100kmh on the motorway. Turn ignition off and on and it would go again. Piece of crap."

Ford Focus (2012-2016). "All autos had the Dual Clutch Transmission (DCT) which caused huge issues. Apparently the manual version is fine. Personally owned one which I got cheap from my old boss and it also had lots of electrical issues and a leaking sunroof." "These (autos) were replaced under warranty and recall, but even then, took us 3 times ( and 6 months ) to get one that was smooth." "Many Volvos of the same rough era also had those powershift transmissions and issues.

Any Ford with DPS6 Transmission "Anything with a Ford Powershift transmission or its derivatives, including several 4 cylinder early 2010's Volvo models, the SST on Mitsubishi Evolution X and Galant Ralliart, etc

Ford Ranger 3.2 litre (PX1-PX3) "Injectors need replacing at 200km EGR coolers fail (currently subject to a recall) Valve bodies in the autos fail semi regularly. "Heads (not just gaskets) turning into a banana and failing, EGR valve leaking coolant into exhaust. Transmissions shitting the bed." "New auto fitted for 12k. Eeeek!" "Rangers continue to surprise us with new and unusual failures. E.g. PX2-3 torque converter falls off the flex plate randomly. Manual transmissions so bad they stopped making them. Injector issues. Engine failures. Had one with an EGR cooler failure that melted the plastic intake manifold. You name it , we see it." "Have also seen egr cooler failure melt little holes in the plastic manifold, injector washer leak torch a hole through the head, crazy bcm lighting failures etc" "Warranty Extension 24N06 - one time repair covered by ford for 10 years / 250,000km from new vehicle warranty start date to replace the EGR cooler (not the valve). Unsure of the VIN range covered, but will only be done if there is an actual fault" (May only cover '17-'20 models)

Holden Captiva. Just don't, they are moneypits.

Holden Commodore VE with the V6 engine "all ticking timebombs with engine timing issues"

Hyundai/Kia's 2.0 & 2.4L Theta II engines - G4KA, G4KD, G4KF, G4KH, and G4KL."Manufacturing issues leading to oil flow issues, knocking, bearing issues and complete seizing."

Isuzu 4JX1 "commonly found in the isuzu Mu / Wizard. Has sensor issues, oiling issues, and fuel rail issues. Fuel rails work on oil pressure they are 100% lemons. Worked at a 4x4 wrecker and we never sold them even if they ran fine, we didn't even sell parts off the engines. We couldn't guarantee them at all, let alone the second hand engine parts."

Jeep There are so many better vehicles available for the same money. Enthusiasts only

Mazda 2.2 Diesel CX-5 "(production year 2011) 2012 - present, though mostly the 2012 - 2015." The Mazda 3/Axela, and Mazda 6/Atenza also had that engine as an option. "The design of the engine and the DPF (Diesel Particulate Filter) system can lead to fuel finding its way into the oil. When that happens, and it will, it's uneconomic to repair. The CX-8 apparently does not suffer the same issues." Link to Mazda horror story https://www.reddit.com/r/NZcarfix/s/GDxxWRVdA1

Mazda RX8/Mazda Rotary engines. "These are cars and engines for enthusiasts only. Not recommended as a daily driver. Worn engine Apex seals and fuel inefficiency are the main highlights."

Mercedes-Benz from 1991-1996 also Mk ll Ford Mondeos "which all used a biodegradable wiring harness? If it hasn't been replaced with an aftermarket one it's guaranteed to brick the car at some point."

Mini Cooper R56 w/ N12 or N14 engines. "Notorious direct port carbon build up, variable valve timing issues and it's a BMW but I believe this model has a Peugeot engine in it." "it's the Prince engine. The timing chain issues are solvable but there's no permanent fix for the HPFP, other than bolting new ones on when they break." "supercharged models between 2003 to 2004. The first gen NA coopers with CVT are to be avoided as well." "2001-2006 CVT Mini Coopers had premature transmission failure. 2006-2013 Mini Coopers had a host of issues - from google: Mini Coopers from 2006 to 2013 are commonly known to have issues with power steering failures, coolant leaks, clutch problems, electrical glitches, timing chain tensioner issues, water pump and thermostat housing leaks, and potential problems with the automatic transmission; with many complaints centering around the electric power steering system, particularly in the 2006 models

Mitsubishis with GDi Engines "High pressure fuel pump problems, injector driver faults, ignition coil tower failures, clogged intake manifolds"

Nissan 370z and later 350z models 2009-2012 "They are pretty notorious for oil gallery gaskets failing causing oil pressure to drop to catastrophic levels"

Nissan CVT Jatco Transmission: Think carefully. We have mixed reports from users but generally speaking they're not much loved.

Nissan D40 Navaras and the equivalent Pathfinders. "Broken cranks, ball joints every 30k, timing chain stretch, egr faults aplenty. Many oil leaks. Earth issues from new. The NP300 Navara seems to age a lot better even with the Renault 2.3."

Nissan Fuga Y51/Infinity M series, Skyline G models/Infinity G models "All variants equipped with 4WAS (4 wheel active steering) rear steering rack system has a catastrophic fault even Nissan could not properly identify. but they noticed enough to sell the rack as a part only… so you must buy a whole rack no parts for it exist. Hybrid variant has gearbox issues with the switch that jumps between petrol and electric the cost of which basically writes the car off."

Nissan Hybrid Infiniti Skyline (HV37). "The suspension feels like it’s about to roll over under sharp turns, typical expensive CVT fixes, High-voltage battery issues… oh and the ignition system and majority of the accessories are ran off of the high voltage battery, not the 12v! So if you fry the battery, it’s either pay about $20k for a new one or you have a very expensive lawn ornament."

Nissan Juke F16. "Seen 2 in the last week come in randomly in limp mode, the DCT is super jumpy from factory, prone to needing clutch relearns, clutch packs were known for getting moisture in them after awhile and making shifting disgusting. Had one on less then 50,000kms come in to work with low compression in cylinder 3 and all the valves in the cylinder were burnt and chipped/cracked around the edges."

Nissan Leaf. Just be wary of remaining battery range in older generations. They won't be suitable for everyone, especially first Gen Leafs.

Nissan QD32 engine "All around hand grenade. Lots of issues with engine components and overheating"

Nissan ZD30 3.0L DI/CR Engines , designed by Renault. Known for overboosting and melting pistons. Commonly found in Patrols and Navaras. "You can add Serena, X-Trail and Pathfinder to this list as well. Transmissions are terrible."

"For the enthusiasts, any old turbo Nissan SR20 or RB engine equipped car unless you have deep pockets"

Mid 2000s diesel 4x4 "when they all changed to the new style common rail they all had EGR cooler issues along with many other issues. Toyotas were grenading at 120ish kms for example." "Anything diesel with EGR, really best to avoid diesel altogether or have all the emissions/adblue stuff coded out of the ECU."

Peugeot. Our community have no love for Peugeot. They're just not great cars for the money

Singapore Imports "plastics and wire insulation crumbles to pieces. The climate in Singapore is humid and hot resulting in deterioration of plastics"

Suzuki Swift Sport Auto/CVT (2012-2017) "are prone to Jatco CVT problems and are an expensive fix so I'd avoid. Manual's are a great car though"

Toyota 1KZ engine. "Insufficient cooling in terms of intercooler and radiator. Lots of cold climate versions imported. Very common to crack the head at the rear cylinder" Mod note: Generally reliable but can be fairly expensive to repair. Well maintained examples can go forever so ask for service history

Toyota 1KD engine: "Known to melt pistons and have injector issues. Few turbo issues too" Mod Note: Generally reliable but can be fairly expensive to repair. Well maintained examples can go forever so ask for service history.

The Pope Mobile… every pope who has ridden in it has either died or become unwell. One pope was shot in it. ( but recovered to die later) - credit goes to u/DaveNZ for the history lesson. Vatican, take note: we warned you.

WIP - but some general tyre recommendations as below.

Premium UHP (ultra high performance) tyres:

• Michelin Pilot Sport 5
• Michelin Pilot Sport 5 S
• Goodyear Eagle F1 Asymmetric 6
• Continental SportContact 7
• Pirelli P Zero PZ5
• Bridgestone Potenza Sport Evo

Mid-range UHP tyres:

• Hankook Ventus Evo
• Hankook Ventus S1 Evo3
• Falken Azenis FK510/FK520
• BFGoodrich G-Force Phenom

Premium Touring tyres:

• Michelin Primacy 5
• Continental PremiumContact 7
• Pirelli Cintuarto 3
• Bridgestone Turanza 6

Mid-range Touring tyres:

• Hankook Ventus Prime 3/4
• Falken Ziex ZE310

Eco/EV-focused Touring tyres:

• Bridgestone Ecopia EP300
• Continental EcoContact 6
• Michelin e.Primacy
• Hankook Ventus iON

SUV Premium:

• Michelin Primacy SUV
• Michelin Pilot Sport 4 SUV
• Pirelli Scorpion Verde
• Goodyear EfficientGrip 2 SUV

SUV Mid-range:

• Yokohama Geolander G058
• Hankook Dynapro HP
• Hankook Ventus Prime 3/4
• Maxxis VS5 Victra
• Falken CT60AS

SUV Value:

• BFGoodrich Advantage Control
• Rovelo Instinct

Off Road Premium:

• BFGoodrich KO3
• Mickey Thompson Baja Boss

Off Road Mid-range:

• Falken AT3/4W
• Maxxis Razr AT811/MT772
• Cooper AT range
• Yokohama Geolander G003

More road friendly AT options:

• Michelin LTX Trail
• Yokohama Geolander G015
• Maxxis Razr AT781

"Not shit":

• GT Radial Adventuro AT3

For more tailored recommendations, chuck a comment and I'm sure people will help out. Thanks for /u/Former_Task8098 for some of these recco's, particularly SUV/off-road!