Best ever V10s: Alonso's championship-winning 3.5-litre Renault F1 engine

Next year, F1 cars will switch to new hybrid turbo V6 power units deploying a greater share of energy from the electrical element despite the removal of the MGU-H and... yep, you’ve tuned out, haven’t you? Can’t blame you.

Amid rumours of the less powerful engines actually slowing down on long straights due to depleted batteries, there’s all sorts of disquiet about the direction F1’s efficiency obsessed propulsion rules are taking. Especially when the current crop of engines are the most thermally efficient combustion engines in all of motoring history, and from 2026 the grid will sip exclusively sustainable fuels. In that case, why not just bring back shrieking, fire spitting, lighter, simpler, cheaper V10s?

Here’s a reminder of what we’re missing: the quite exquisite Renault R25 from 2005. This diminutive, razor sharp dart was the last Formula One car to win a world championship with V10 power, in the hands of Fernando Alonso. It’s easy to spot where it aces what modern F1 gets so wrong – it’s narrow, agile, short in the wheelbase and the aero devices are intricate without being contrived. There’s no overtake button boost, no DRS. And a decent livery. It seems to have more in common with your local arrive ’n’ drive kart than the bloated F1 crop we have today.

At ankle height lives the 72º 3.5-litre Renault RS25. It redlines at 19,000rpm and generates 900+bhp despite weighing less than 100kg. So the whole car offers 1,500bhp per tonne – more than double the power to weight ratio of a Bugatti Chiron. It’s a masterpiece in miniature engineering. Which you’d want given each engine cost £170k.

The R25 wasn’t a clean sweep car. It actually lost the outright win scrap during its season 10–8 to McLaren, but it was consistent and reliable, only failing to score points at two events. And when Alonso was reacquainted with it at the 2021 Abu Dhabi Grand Prix, the two time champ called it “small, like a toy, but very special” and reportedly lapped the circuit faster than any of the official timed laps during the race the following day.

This car has Top Gear history too. It isn’t the machine that blitzed the track in 59 seconds – that was its immediate predecessor, the R24. But it did make an appearance on episode 10 of series eight, when Richard Hammond demonstrated just how otherworldly F1 performance is to a mere mortal by having a go at driving the R25. And spinning off after half a lap.

Word is that if V10s were to replace hybrids, the likes of Mercedes, Audi and Honda would tear up their F1 engine supply contracts due to lack of road relevance. Don’t let the pit garage door hit you on the way out...

Renault R25

Price new (2005): £5m
Price now: £500,000
Engine: 3,000cc V10, 900+bhp @ 19,000rpm, 324Ib ft @ 16,400rpm
Transmission: 6spd semi-auto, RWD
Performance: 0-62mph in 2.0secs (est), 210mph
Weight: 605kg

Photography: Jonny Fleetwood & Alex Tapley