The great cars let down by their engines

It might be hideous unreliability, terrible refinement or a lack of power, or a combination of all three, but by choosing the wrong engine for these cars, they were all doomed from the outset:

With its gorgeous lines and sweet handling, the MGA is a highly desirable classic. Most came with a 1.5 or 1.6-litre engine with overhead valves, but more than 2000 got a twin-cam engine developed from the standard MGA's B-Series unit.

Fitted only to the MGA, this double overhead-cam engine demanded top-grade fuel and the ignition timing to be spot on. Without both at all times, the pistons were easily holed and with a propensity to burn oil even when in rude health, buyers avoided the MGA Twin Cam at all costs.

We're not mocking Chrysler by including this car that never reached full-scale production – after all, where would we be if car makers didn't push the boundaries? But the Chrysler Gas Turbine was an experiment too far.

Just 50 were made and lent to families for real-world evaluation; they concluded that limited acceleration, shocking fuel consumption, a complicated starting procedure and poor refinement were too high a price to pay, and a regular V8 would do the job far better.

The Imp had the makings of a truly great car, with its light weight, slick gear change and zesty engine. But while the all-aluminium 875cc water-cooled 'four' mounted in the rear ensured the Imp was tremendous fun to drive – genuinely good enough to take on the Mini – it was also this powerplant that would be one of the Imp's many failings.

As well as problems with the pneumatic throttle of early cars, overheating often led to blown head gaskets and warped cylinder heads or even distorted blocks. Later cars were largely sorted, but the Imp's reputation was shattered by then.

Of all the sub-standard powerplants here, the Ro80's Wankel unit was perhaps the most catastrophically weak – it was bad enough it nearly destroyed the company that made it. While the Ro80 was a brilliant car with its ultra-aerodynamic design and semi-automatic transmission, total engine failures within the first 10,000 miles were common thanks to the rotor tips wearing, leading to a lack of compression.

Warranty claims spiralled out of control, leading to NSU collapsing into the arms of Volkswagen in 1969. The NSU name disappeared from view in 1977, when the Ro80 also died.

We're stretching the great cars bit with this one admittedly, but you can't deny that the Austin 3-Litre is an intriguing car that could (should?) have been great. Large and luxurious, the 3-Litre should have featured decent ride and handling but had neither, while its smooth straight-six was based on the one seen in the Austin Healey 3000.

Sadly it didn't prove as long-lived in the 3-Litre though and many of the 9992 examples made were scrapped because of premature engine failure.

An affordable four-seater convertible with V8 power – what's not to like? Especially when it's also got smart Michelotti styling. But that V8 was a 3.0-litre unit unique to the Stag and it suffered from a litany of glitches including weak timing chains, warped cylinder heads and poor-quality castings that led to a lack of coolant flow and consequent overheating.

In seven years just 25,939 were made, and just 10% of them made it to America which was a key would-be market. British Leyland had hoped for so much more: a car to rival the Mercedes SL in both sales and stature.

A two-seater sports car resulting from a collaboration between Jensen and Healey, powered by a Lotus engine. The world's first production car to feature an engine with four valves per cylinder, the Jensen-Healey should have been sensational, but complying with US safety legislation spoiled the looks and that twin-cam 16-valve engine turned out to be a complete disaster.

Prone to overheating resulting in warped cylinder heads, the Jensen Healey's powerplant was just one of many weaknesses that buyers had to contend with.

Here's a conundrum for you; the Triumph Dolomite Sprint is here because of its engine, and despite it. The Sprint was based on Triumph's Dolomite saloon so it offered performance with luxury. But the all-alloy engine was prone to overheating leading to blown head gaskets and warped cylinder heads, the whole thing often kicked off by the viscous fan seizing up.

Sure it was boxy and offered little in the way of driving pleasure, but the Volvo 260 provided safe and comfortable family transport and it was superbly well made at a time when many rivals had the durability of rice paper.

However, the all-aluminium PRV 2664cc V6 engine developed between Peugeot, Renault and Volvo (hence its PRV tag) was shockingly unreliable, with camshafts wearing at a ferocious rate and overheating the norm, leading to a distorted block. This engine would later be fitted to the DeLorean and Renault-Alpine GTA and A610.

Lancia has an enviable heritage when it comes to innovation, but by the 1970s it had disasters on its hands such as the Beta and Gamma. The latter was a luxury saloon or coupé with a 2.5-litre flat-four that drove the front wheels – or at least it did when it was working. But on full steering lock the cam belts were prone to slipping off their guides, wrecking the pistons and valves. Not clever.

Fuel crises throughout the 1970s led US car makers to get inventive with ways to cut fuel consumption. GM came up with the bright idea of resorting to diesel power, but its 5.7-litre V8 used the same head bolts as its petrol units.

The much higher compression ratios led to those bolts stretching, then blown head gaskets, and cylinders filling up with coolant leading to bent con-rods. GM was inundated with warranty claims but persisted with diesel power right the way through to 1985 when it finally gave up.

The Mercedes S-Class has always been a trailblazer when it comes to performance, luxury and safety. So when Mercedes introduced the first ever turbocharged diesel-powered saloon, expectations were high.

Sadly those expectations were misplaced though; the five-cylinder engine offered all of 110bhp and 168lb ft of torque to give a top speed of just 103mph. The 300SD was offered only in the US, but unsurprisingly, sales were fairly small and in any case it's reason for being - high fuel prices - waned and the need for it largely disappeared.

Those pesky Californian emissions regulations led to a raft of emasculated muscle and sports cars, but surely the saddest of them all was this: a Corvette with a 305ci (5.0-litre) V8 rated at just 180bhp, just for sale in the Golden State. Even worse, there was no manual gearbox option with all Corvette 305 Californias getting a three-speed slush box to reduce performance even further.

It's not as though excellent economy was the pay off; owners got just 15mpg or so. No wonder production was canned after just one year.

By not purchasing a diesel-engined Cadillac in the early 1980s, you dodged a bullet. Well, seemingly. But the petrol-powered V8 alternative came with displacement on demand technology called V8-6-4, which shut down pairs of cylinders depending on the load placed on the engine.

GM bravely installed the system into the entire 1981 Cadillac lineup (apart from its diesels). The problem was that the electronics were in their infancy with sluggish computing power, and the system didn't work which made the cars pretty much undriveable. Dealers were told to bypass the system so the engine just ran on all eight cylinders all of the time. The system was dropped after just one model year, and it would be another 20 or so years before cylinder deactivation came back into vogue - this time aided by much more muscular computing power.

PICTURE: Cadillac Seville

The original Chevrolet Camaro looked great and packed some serious muscle if you bought the right edition. But over time things got watered down ever further and by 1982 you could buy a Camaro with a 2.5-litre four-cylinder engine rated at just 92bhp. That was just about enough to get the Chevy up to 100mph. The muscle car that wasn't.

American car makers are notoriously conservative, which is why they've made very few mid-engined sports cars over the years. One of the few is the Pontiac Fiero which looked promising when it was unveiled in 1983, but the cast-iron 2.5-litre four-pot was designed for low-down torque rather than high revs – not ideal for a sports car.

But it was much worse than that; the engine's con-rods were poorly made and had a tendency to snap and punch a hole in the block, leading to oil pouring onto the hot exhaust which would then ignite.

A luxurious two-seater convertible should have been a sure-fire winner, but Chrysler has a history of coming up with great concepts that are poorly executed. And so it was with the Chrysler TC by Maserati, which saw US and Italian brands collaborating to create a car that looked rather smart, handled disappointingly, but was a disaster thanks to a turbocharged 2.2-litre four-cylinder engine that was as reliable as you'd expect an eighties Maserati unit to be.

The Range Rover Classic is quite rightly a landmark car, and in V8 petrol form it's a hugely desirable classic. Launched in 1970 it would take another 16 years before a diesel-engined RR was offered, but the choice of a 2.4-litre VM unit was a poor one because while it was turbocharged it was utterly gutless, to the point that performance was all but non-existent.

Despite being an in-line four-cylinder engine this powerplant featured no fewer than four head gaskets – and they failed with monotonous regularity.

Developed for the military as the High Mobility Multi-Purpose Wheeled Vehicle (HMMWV), the Hummer (derived from Humvee) should have been indestructible. And so most of it was, but H1s built between 1996 and 2000 were fitted with a turbodiesel engine which suffered from cracking of number eight cylinder, due to a casting flaw.

Once the engine failed, wholesale replacement was the only fix – and some cars got one wrecked engine only for another flawed unit to then be fitted…

With its cheeky looks, brilliant ride/handling balance thanks to the use of Hydragas suspension, and affordability, the mid-engined MGF was one of the greatest sports cars of the 1990s. But that mid-mounted powerplant was MG-Rover's K-Series unit which was notorious for blowing head gaskets thanks to its low coolant capacity. The slightest leak meant the engine would overheat, taking the head gasket with it.

TVR was never short of ambition, and creating its own engine from scratch was quite a commitment. That first engine was a V8 (dubbed AJP8), but out of that came the Speed Six unit, a straight-six that was light and powerful – but also hideously unreliable.

TVR had to rebuild or replace lots of these engines under warranty, thanks to numerous top-end failures as a result of damaged camshafts and valve guides. TVR went out of business in 2006.

Lots of companies looked at building rotary-engined cars in the late 1960s and early 1970s but they were wary after the demise of NSU. There are inherent problems with the rotary engine design but despite this Mazda stuck with the concept from the late 1960s onwards.

Years after everybody else had given up on Wankel power the Mazda RX-8 arrived and while the car looked superb and handled brilliantly, that rotor tip weakness had never really gone away, with engines often losing compression well before 100,000 miles had been clocked up.

We've singled out the E90 BMW 3 Series here, but the N47 diesel engine that's the reason for its inclusion in this list was also fitted to the 1 Series (E81) and 5 Series (E60). All of these cars were hugely desirable, but that N47 could prove to be a nightmare for owners, as its timing chain could wear and then fail.

Rattling galore gave away any impending failure, but because the chain was buried away at the back of the engine, the cost of replacing the chain could exceed the value of the car.

The Land Rover Discovery 3 was the first luxury off-roader that could genuinely go anywhere and seat seven adults in comfort. Smartly designed and wonderful to drive, the 2.7-litre TDV6 engine, later enlarged to three litres, was smooth and torquey.

This powerplant was the result of a collaboration between Ford and France's PSA and as Discos racked up the miles it became clear that there was a major weakness; the crankshafts could snap with no warning. It's not restricted to the Discovery either; a host of other Jaguars and Land Rovers suffered from the same problem.