At the Geneva Motor Show this month I took a look at a new variant of the E-Class saloon due later this year.

The E300 Bluetec Hybrid was remarkable for how similar it was to the E220 CDI I’ve got. The new derivative will be Mercedes-Benz’s first diesel-electric hybrid, and under the bonnet there is a version of the engine I have in mine.

The 2,143cc four-cylinder diesel is available in a number of Mercedes-Benz models and in the E-Class is offered as a 136bhp E200 CDI, in 170bhp E220 CDI guise in the car we’re running, and also with twin-turbos as the 204bhp E250 CDI a step further up the E-Class range.

It’s the higher-power version used in the E300 Bluetec Hybrid, with the electric motor of the hybrid components also making a contribution to boosting performance.

In terms of fuel consumption, preliminary figures for the E300 Bluetec Hybrid raise the bar for cars this size with 68.9mpg and 109g/km expected. This compares very favourably with the official 132g/km and 57.6mpg for the 17-inch-wheeled E220 CDI with seven-speed automatic transmission, although there is likely to be a substantial price premium for the technology in the hybrid over our car.

But perhaps the most remarkable aspect about the hybrid was when I looked in the boot. The hi-tech components didn’t appear to have affected the 540-litre boot space of the E-Class saloon, unlike other hybrids in this class which tend to be compromised with battery pack and other components stealing luggage space.

In terms of overall costs, our fleet focused E220 CDI Executive SE is highly competitive, but we expect the new diesel hybrid to raise a few eyebrows when it launches.