BOARDROOM expresses that were originally very expensive are not for the faint hearted secondhand - even though older models can come at real bargain prices.

They are almost all thirsty, expensive to insure and costly to fix when they go wrong.

But still, few cars are more superbly comfortable and capable than the Mercedes S-Class, which has regularly been at the top of the luxury car league for years, often cited as the ‘best car in the world'.

The flagship of the Mercedes brand has always showcased new technology and it offers pretty much the last word in luxury, pace and refinement, while also managing to be as good to drive as it is to be chauffeured in.

When the last model came out in 2014 - it was replaced last year - the tradition continued and it won accolades from all who drove it.

It had some of the most advanced and clever gizmos available, including a semi-autonomous driving system that used sat nav to slow for and steer.

And there was another electronic setup that could actually read the surface of the road ahead and adjust the suspension to compensate for it.

From 2014 to 2019 there was a wide range of engines, including two diesels and three hybrids and all drove through a very smooth changing nine-speed automatic gearbox.

The standard wheelbase was only available in a few cars - not that they were short on anything - and all the rest had the longer version with huge rear legroom.

The two diesels have the same 3.0-litre V6. The S350d has 254bhp and a zero to 60 miles an hour time of 6.6 seconds, with 50 miles per gallon.

The S300h is a diesel/electric hybrid with 227bhp, 0 to 60mph in 7.4 seconds and 61mpg.

The smallest petrol models - the S450 and S500 - both have a 3.0-litre engine, producing 361 or 428bhp and covering the 60mph sprint in 4.9 or 4.6 seconds. They both have an average of 36mpg.

There was also a 4.7 V8 S500 with 448bhp , 0 to 60mph in the same time as the 3 litre and 32mpg.

And then comes the S600, which has a 5.5 litre V8 and 576bhp, and gets to 60 in 4 seconds. At best, this will do 25 mpg.

The S400h hybrid is petrol electric and has 328bhp. It covers the sprint in 6.6 seconds and could do 42mpg, while the plug-in hybrid S500h has a total of 442bhp, covers the sprint in five seconds and is rated at 128 miles per gallon. This model can cover about 30 miles on battery power alone.

Needless to say, a car at this level has superb refinement in all situations and marvellous comfort over any and every surface.

Yet is also handles much better than most drivers would believe, with informative steering and very good grip and road holding.

Never buy without full service history. You need to know it has all been done to make sure you have as few problems as possible.

But Mercedes'reliability has not been very good over the past few years. In a recent survey, the company came 26 out of 31.

There have been a number of recalls on these latest S-Class models too, so check to see that modifications have been carried out.

The interior is beautiful, stylish and sophisticated, blending classic and modern touches seamlessly.

Trim levels seem to go with engine choices and all have a wide range of kit. Mid-range AMG Line has keyless start and entry, 19-inch alloys, cruise control, heated leatherelectric front seats with lumbar adjustment and memory, parking sensors all round, rear-view camera, adaptive LED headlights andan excellent infotainment system with Apple CarPlay, Android Auto, sat nav, and a wireless smartphone charger.

It also has self-adjusting air suspension, multifunction leather steering wheel, electrically adjustable steering column, metallic paint and wood trim.

All are very safe and have loads of electronic wizardry to keep you on the straight and narrow.

Pay around £19,300 for a '15 15-reg S350d SE-Line diesel, or £32,000 for a '17 17-reg S400h AMG-Line hybrid.