Space and practicality
While posited as an E-Class coupe, the CLK's a C-Class underneath and that means C-Class room on the inside. With a plunging roof line and only two doors to get at the interior space, that means it's somewhat limited, especially if you're in the back.
That said, headroom and legroom is tolerable for shorter journeys and children won't mind all that much – if you don't mind them kneeing the back of your seat. There are three seats in the back, but the middle one straddles a colossal transmission tunnel, making what little legroom there is even less.
The coupe has a 435-litre boot, which is definitely decent. Even the convertible has 390-litres, thanks to the roof taking up some of the space, but that's still the size of a modern hatchback's boot. The space is not quite as usable as with a hatchback, but there is still the option to fold the rear seats down.
Although the CLK was never tested by EuroNCAP, it was based on the C-Class which was tested in 2002 and 2007. In both cases the car scored five stars, with three stars for child safety in the enhanced 2007 test. Although these results cannot be compared to modern crash tests, they were at least safe for the era and the CLK had six airbags and ESP as standard.
Engines
At the end of its life there were seven engine options for the CLK, two diesel and five petrol.
The 220CDI, a 2.2-litre diesel, was only available on the coupe model. This offered 147hp, which was enough for a 0-60mph sprint of 10.0s and a 137mph top speed. Emissions rated at a lowest of 169g/km, depending on specification, equivalent to 44.1mpg.
Above this was the 3.0-litre, six-cylinder 320CDI diesel. This 221hp unit still rated at 39.8mpg (193g/km), improving the 0-60mph time to 8.4s and lifting the top speed up to 150mph.
Petrol power started with the supercharged, 1.8-litre 200 Kompressor. With 181hp, this achieved the 60mph sprint in 8.6s (9.1s for the convertible) and a top speed of 147mph. CO2 emissions rated as low as 198g/km, depending on trim level and wheels, for a 34.0mpg fuel economy (32.8mpg in the convertible).
The lowest output six-cylinder petrol was the 3.0-litre 280. With 229hp, the 0-60mph time fell another 1.4s to 7.2s for the coupe and 7.7s for the convertible. Top speed was limited to 155mph, as with all more powerful options, while both convertible and coupe returned 29mpg with this engine, at around 220g/km CO2.
A larger version of the engine was the 3.5-litre 350. Although it only had 39hp more, at 268hp, 0-60mph times fell by another second – 6.2s for the coupe, 6.7s in the convertible – while keeping fuel economy close to the smaller engine at 28.5mpg
The regular CLK range was crowned by the CLK500, a 5.5-litre V8. This was considerably more powerful, with 382hp, making the sprint to 60mph a matter of just five seconds (and the convertible just 0.1s further back). Fuel economy just about dips below 25mpg, with 24.8 for the coupe and 24.4 for the convertible, depending on your trim choices.
However, the cherry on the cake is the 475hp, 6.2-litre V8 CLK63 AMG. Although still limited to 155mph, it manages 0-60mph in just 4.4s (4.5s for the convertible version – making it one of the quickest convertible cars made to that point in time). You'll pay a 19.9mpg penalty for that though, falling to 18mpg if you opt for the 25hp extra in the Black Series car.
Running costs
The CLK won't be a cheap car to run by any stretch of the imagination, unless you limit yourself to lower-power cars like the 220CDI and 200 Kompressor, but then you shouldn't expect it to be as it's a large, premium coupe or cabriolet.
Even so, 44mpg combined at best is not a great showing, especially for a 2.2-litre diesel. However, even though that's measured using the optimistic NEDC emission and economy test, the bulk of the CLK range is powered by large, naturally-aspirated petrol engines, so you shouldn't see figures too radically different from the official on-paper economy – even if the on-paper economy is poor.
The second-generation CLK, and even the facelift, overlaps a change in VED regulations. This means that some of the thirstier models may cost you £210 a year less to tax if you buy a car registered before 23rd March 2006 – enough for a couple of extra tanks of fuel a year! It may be worth your while to shop a little carefully with this in mind.
Insurance is a mixed bag, but again on the expensive side. The entry level cars are in group 33, or 38 for the convertible, and that's a little steep for a car without satnav that's no quicker than a middling hatchback. However, even the CLK500 is only group 44 (47 for the convertible), so not as expensive as you may think. The AMG cars are, of course, group 50.
By now, any CLK will have done most of the depreciating that it will ever do, so you won't lose much as time passes. The significant parts-sharing with the C-Class will mean that parts availability is good, and any repairs needed ought not to be too costly either.