There I was, cruising along the inside lane of the M4 at my usual circa-65mph, congratulating myself on the energy I was saving, when another Leapmotor C10, metallic green just like mine, steamed past in the overtaking lane, briskly dispatching all the quicker traffic as it went.

It made me wonder what I was doing. I have been driving electric cars and plug-in hybrids most of the time for the past four years or so and have become used to easing along motorways in the inside lanes, telling myself (usually accurately) that there's only a minute or two's difference in journey time on my average 100-mile drives between cruising easily and clogging it.

I have no way of knowing whether this much faster C10 was a purely battery-driven version or another range-extender like mine (the latter's exhaust pipe is hard to spot), but it looked pleasantly purposeful forging along, rather than somewhat apologetic like the crawling versions I've seen, so I decided to try driving a fair bit more quickly over distance to see whether I would enjoy it and what damage this would do to the economy.

So I set off at a decent lick, using the smooth and easy torque without my usual qualms and taking no significant account of the down slopes that I've instinctively learned to turn into charging opportunities. It felt a bit irresponsible but rather bold, and the car felt eager as you'd expect of a machine that puts 236lb ft of torque under your right foot without even having to idle to do it. A fast cruise was smooth and easy to maintain (that torque keeps you speeding easily up long slopes) and there was very little vibration.

As it happens, the C10 generates very little wind noise, even if road noise is inclined to make up for it on the older, noisier bitumen surfaces that seem to abound in the UK.

Going even quicker, the C10 felt well planted and directionally stable through its wheel, probably because, even though it's a big car in which you sit higher than in a saloon, the overhangs are short, the wheelbase is long and the centre of gravity is low. Steering corrections are small and hardly necessary.

I kept this up for about 80 miles, eyeballing the trip computer on the straight-ahead driver's screen. I'm used to seeing about 4.2mpkWh and 48-52mpg as the powertrain swaps between petrol and electric; on this mainly flat motorway the battery contributed very little and the petrol engine returned about 10mpg less, still promising around 400 miles from a tankful before the battery (maintaining a potential contribution of 60 miles) chimed in.

Of course, I knew that as soon as I reached a town or a B-road the MPG would climb again to erase any impression that quicker cruising is costly; in this 'Hybrid EV' it isn't.

Many drivers are impervious to consistently good economy, possibly because many fuel bills are paid by employers. But I find it consistently pleases me, which makes driving the C10 a particular pleasure. It never seems to get truly thirsty. In fact, the bong warning for low fuel or low charge takes me by surprise, just as refuelling always seems pretty cheap.

Chuck in the long range (the promise of 605 petrol-electric miles seems truthful) and you have a seriously economical all-rounder - however you choose to drive it.