Ford Fiesta 1.0 MHEV ST-Line X 2020 UK review

Battery boost brings small but meaningful economy gains to Ford's stellar supermini Ford's electrification efforts may not kick into high gear until the 2021 launch of the Mustang Mach-e, but it continues to add mild-hybrid power to its model line-up in the meantime.The Fiesta is the latest to receive battery assistance, joining the Puma and Focus with a 48V architecture that promises to bring modest fuel and emissions savings to the (already rather efficient) 1.0-litre three-pot Ecoboost petrol engine. It's a familiar set-up, with a belt-driven starter motor feeding in extra torque courtesy of a small lithium ion battery that relies entirely on regenerative braking to charge itself. This combination cuts down on turbo lag, lets the stop/start system activate while coasting below 15mph and makes acceleration that little bit peppier. It has also allowed Ford to add a larger turbocharger and lower the engine's compression ratio, for what it claims are 5% efficiency gains over a non-hybrid engine.The battery introduces only a minor weight penalty, so performance remains largely unchanged, with 0-62mph in 9.4sec and a top speed of 126mph. There's a slightly nippier 153bhp version that dips under nine seconds, but neither can be had with an automatic transmission.Mild-hybrid power arrives as part of a wider update for 2020, which sees all Fiestas with Cross Traffic Alert gain active braking, and ST-Line models like our test car get a perpendicular park function for the active park assist. The optional B&O Play sound system also has its subwoofer relocated, so you no longer have to choose between banging tunes and a bit more boot space.