Seat Leon FR 1.0 eTSI – long-term review

Our Seat Leon eTSI is, officially, a hybrid. But in everyday driving, you have literally no sense of any clever hybrid stuff going on under the bonnet.
 
This may be because there isn’t a whole lot of clever hybrid stuff going on under the bonnet. No, actually, that’s unfair. There is some genuinely smart petrol-electric stuff at play here, but it’s happening very much at the micro rather than macro level. 
 
The Leon eTSI is what Seat describes as a ‘mild hybrid’. This is a fair description. On the Scoville scale, we’re talking ‘bell pepper’ rather than ‘Carolina Reaper’ levels of hybrid spiciness here. 
 
Here’s how it works. In addition to the standard 12-volt battery that feeds the ancillaries and starter motor, the Leon also gets a compact 48-volt lithium ion battery recharged by energy harvested under braking, and driving something described as a ‘belt-driven starter-alternator’, which effectively functions as a mini e-motor. No plugging into the mains here (there is a plug-in Leon available too, but that's a story for another day).
 
This 48-volt system provides a smidge of low-end torque to eliminate turbo lag from the 1.0-litre three-cylinder. I can report I have noticed no turbo lag. And, though you can’t drive this Leon on electric power alone, once you’re up to speed it’s capable of cutting the engine and ‘coasting’ on that squeeze of e-torque. 
 
Mild it may be, but the results are impressive. After 2000-odd miles of motoring, I’m averaging pretty much bang-on 50mpg in the Leon, which is, I’m pretty sure, the best economy I’ve ever seen from a test car. For context, it’s a few mpg better than I managed from the Audi A1 I ran a couple of years ago, which used effectively the same three-cylinder petrol engine (albeit in a marginally higher state of tune). Given the Leon is a bigger, heavier car than the A1, I’d say that’s a decent result. 
 
Interesting it’s also about 10mpg better than I averaged, last year, over 5000-odd miles in a Mazda CX-30, the one with the clever new SkyActive X compression-ignition petrol engine. Now, you could – and indeed should – point out that the CX-30 is a taller car than the Leon, more crossover than hatch, and has a chunk more power for good measure. But still, 25 per cent more economical is… a lot.
 
Of course it’s difficult to know how much frugality the Leon’s mild hybridity is adding. Weirdly Seat quotes the non-hybrid 1.0-litre Leon (same engine, no extra 48-volt bits) as boasting fractionally better fuel economy and lower CO2 emissions, which I guess can only reflect the fact the hybrid-stuff’s benefits aren’t picked up on the official WLTP cycle. Whichever way, this sort of mild-hybrid arrangement makes more sense to me than a full-on plug-in hybrid, where you’re effectively lugging around two full powertrains at all times.
 
And put it this way: it’s the first time in a long, long time I’ve been pleasantly rather than unpleasantly surprised by a car’s real-world economy…