RIGHT now, the Mercedes E-Class is the best executive saloon there is. But this is May, and the stunning new BMW 5-Series is due here in September.

Will the label of leading luxury car see-saw back to the Beamer?

In just five short months we'll know the answer, so the superlatives stay stacked with the sought-after Mercedes for now.

The latest E-Class has been here less than a year, and has won much praise for its effortless performance, elegant styling, and vastly enriched interiors.

Trim levels follow the established Mercedes-Benz standard of basic Classic, Elegance and top-spec Avantgarde, and the range starts with the 200 Classic at £24,940. Going up a trim level costs an extra £2,100, or £2,600 if you want the best.

You can pick from five very refined, fleet-footed engines. There's six-cylinder 2.6 and 3.2 units, an eight-cylinder 5.0 beast, and two diesels, a four-cylinder 2.2, and a five-cylinder 2.7, both turbocharged.

If it helps determine your choice of a diesel, the E270 CDi saloon has just been voted best executive class winner by Diesel Car magazine.

On test was the E240 Avantgarde, a 2597cc silver-coated smoothie that sells at £30,640.

Glide along gracefully, or go like the wind, the 177-horsepower engine is at your behest to either purr primly or punch out power through the big four-door saloon's rear wheels.

The supply of surge never runs dry, right up to the 145mph maximum.

The five-speed automatic transmission is as seamless as the delivery, and there's cruise control to de-stress those motorway miles.

With the combined mpg figure at 27.4, it helped that the E240 had the larger, 80 litre, fuel tank fitted. The standard-size E-Class tank holds 65 litres.

Driving the E240 makes for much motoring pleasure. Seats and steering adjust every which way, it's got the poise and balance of a ballet star, and once you accustom yourself to the saloon's size and taut responses, it all feels so fluent and satisfying.

Mercedes-Benz E-Class E240 Avantgarde, £30,640. E-Class range from E200 Classic (£24,940) to E55 AMG (£60,640).

The nose-down stance of the E-Class was given extra purpose with the add-on AMG bodystyling kit (£2,650), sports suspension (£310) and light-alloy wheels (£1,810), although the glass sunroof (£1,200) with solar module (£390) and electric rear roller blind seemed a bit superfluous, given the excellent automatic climate control system.

Other options such as leather upholstery (£950) and an upgraded sound system with satellite navigation (£1,160) and six-disc CD changer (£350), added to those given above, saw the E240 Avantgarde's price soar by a third to £40,995.

The three-year unlimited mileage warranty is a strong selling point, and it is reinforced by an unequalled 30-year (yes, 30 years!) anti-corrosion and breakdown package.

This very clever car also has the Assyst Plus indicator, which tells you the remaining time and distance to the next service, and details the work needed. That's brains behind the beauty, and you can't fail to go the distance in an E-Class with that kind of reassurance behind you.