THE Audi Q7 e-tron is exactly what your accountant ordered.

It makes financial sense to order and run one but you may wonder why you did when its lined up against rivals, including the conventional Audi Q7 stablemates which are easier to live with and may, in some situations, actually return more miles per gallon.

Audi's A3 e-tron was the company's first plug-in family model while the big Q7 SUV e-tron is in a different sector, but still only seats five as the voluminous traction battery pack takes up a lot of rear space but it offers 650 litres rising to 1,835 litres nevertheless.

It starts at £50 under £65,000 and there is a truly typically Audi options list to boost it and create a bespoke model which may be unique to you.

That price puts it outside the UK Government's Plug-In Vehicle Grant but it is still currently exempt from Vehicle Excise Duty because it officially emits just 48g/km and company car drivers using one will pay a lowly 10% Benefit in Kind tax and slip into the London Congestion Charge zone for nothing.

Whatever reason you choose to buy or more probably lease an Audi Q7 e-tron you will immediately feel at home in the luxurious cabin with its fine attention to detail, style and sophistication.

Everything inside looks and feels very good and what you cannot see but experience out of sight is similarly refined in the way it performs as a hybrid.

Start with a gentle throttle and the electric power is immediately available until a firmer foot pulls in the diesel engine.

The familiar 3.0-litre, V6 TDI turbo-diesel engine is mated to a 94kW electric motor driving the quattro four-wheel-drive system through an eight-speed automatic gearbox.

The combined output is 373bhp and 700Nm of torque from 1,250rpm while the acceleration from rest is particularly noteworthy.

Officially, combined cycle fuel economy is up to 156.9mpg with electric power only driving range is up to 34 miles and the two with an overall driving range combining diesel and electric power of up to 820-miles.

On our run we found an overnight charge took it to about 21 miles on electricity before the diesel engine took over and the indicated 300mpg collapsed to under 160mpg overall and fell still further to under 80mpg.

With a longer run it would possibly have dipped into the sub-40mpg sector, and this may be a sore point for buyers who believe they will always get over 300mpg unless they fully understand the e tron's operating requirements to get the most out of the car.

The battery can be fully charged in as little as 2.5 hours via a high output public charge point or domestic dedicated wallbox but it will take eight hours using a conventional 13amp socket.

There are three selectable driving modes. The EV mode is electric power only, Hybrid auto mode decides the most appropriate use of power between diesel and electric and in Hybrid Hold mode the system stores the electric power for use at a later time in the journey when it would be more appropriate.

Standard equipment includes Audi's Virtual Cockpit, predictive efficiency assistant, MMI navigation, smartphone interface, Audi Connect infotainment and e tron connected services.