2026 Ford Mustang RTR Spec 3 | UK Review

An autumnal moorland road in an unhinged (but fully warrantied) 750hp 'Stang? What could go wrong...

The prospect of 750hp for £87k remains mouthwatering, even in a world of easy-won electric performance. Even better? The joyous pairing of numbers comes strapped to one of the tiny handful of manually shifted, purely rear-driven coupes still in existence. Oh, and you’ll be pouring your cash not into the vast accounts of a Chinese conglomerate, but folks operating out of a workshop near Leeds.

Well, at least some of your cash. Speccing up an RTR involves ordering a brand-new, £58k Mustang GT from your local Ford dealer (assuming Chery or BYD haven’t since taken it over) and then calling Motorsport and Performance to order your upgrade. Ask nicely and they can handle the whole transaction.

It’s then a case of choosing how hard you want to go. In stock form, the latest ‘Stang boasts a 453hp, 398lb ft 5.0-litre naturally aspirated V8 good for 0-62mph in 4.4 seconds. RTR’s Spec 2 upgrade costs £15k and brings a visual makeover – with dramatic new aero-carved body panels – and adjustable Tactical Performance suspension that apparently makes your car quicker than a Mustang Dark Horse on circuit. All without the internals being touched.

That’s something the Spec 3 takes care of. A Whipple 3.0-litre supercharger turns the screw to deliver enormous new 750hp and 615lb ft of torque outputs, while the wheels are a newly staggered RTR setup wrapped, thanks to the testing conditions of the Yorkshire lanes we’re about to explore, in Michelin Pilot Sport 4S tyres. All part of M&P’s mission to make your ‘Stang a better all-rounder on British roads.

Going for a Spec 5 would be pushing the limits of ‘all-rounder’, mind; the numbers are a bulky £110k uptick (so about £170k all in) and claims of 870hp and 660lb ft from its Stage 2 supercharger kit, alongside coilovers, a carbon widebody kit and a Borla cat-back active exhaust “tuned by Vaughn Gittin Jr”.

All cars get a dash plaque engraved with Gittin’s signature and an RTR performance shift knob, whether you’ve gone six-speed manual or ten-speed automatic. Yep, you can RTR any spec of Mustang GT, even a cabrio. The best bit? The upgrades are properly Ford-affiliated things nowadays and thus they all come with three years and 36,000 miles of warranty. Even the Spec 5.

Yet it’s this middle-rung Spec 3 which looks to offer the ideal balance of cost and performance. At £27,995 it’s the price of a whole new hatchback – but given it adds almost 300hp it can still withstand such an obtuse comparison. “We can build it around the 2024+ Mustang GT you already own, or supply a brand-new Mustang RTR for you, and shape the build around your own taste, from wheel finish to the details,” Motorsport and Performance says. “Wherever you are in Europe, just bring your car to our workshop in Birstall, West Yorkshire, and we’ll build your Spec 3 here.”

Just one firing of its engine in that Birstall workshop appears to warrant its price tag alone. The car practically rocks on its axles as it starts up and the sound showers down on snapper Habbo and I before the metal rolls up to free us into the Yorkshire hillside. Not without an arduous slog of M62 traffic first, mind. I’m not sure a low-speed trudge past the UK’s most famous mid-motorway farmhouse is quite what Vaughn had in mind when he was tuning this kit, and wending our way along hectic roads in the lashing rain is a proper event. This is a loud car at all speeds – not to mention one which prefers an assertive wielding of its controls.

The moorland roads we’ve pointed ourselves at are mercifully drier, however, and with a touch more warmth in its tyres it quickly coalesces into an almighty thing. It’s always in possession of the pent-up, barely contained energy we all crave from a muscle car, yet the new tyres, diff and suspension overhaul ensure there’s enough feel, accuracy and crucially tension to feel like you can exploit it. The traction control is working hard enough on these autumnal roads that I harbour zero desire to begin loosening it, but its light enough in its touch to not hold back progress. The world of mollycoddling performance EVs allows you to leap in and deploy 700-odd horsepower with nary a care – here, there’s a welcome return to bedding yourself in with a car’s performance. Of strapping on your water wings before exploring the deep end.

This is an especially testing road, one particular section of which ties my otherwise terrific Hyundai i20N in complete knots, and the RTR exhibits plenty of vertical movement while remaining in uncompromising control of itself. It’s evidently a much stiffer, more precise thing than a stock GT and those who want to go hunting M4s and 911s appear to have a car capable of keeping up.

Find an opportunity to hold second or third gear and from 3,000rpm it just tears towards its redline, sounding utterly brilliant the whole way. 7,500rpm sounds more like ten. On track, with speed limits lifted and sufficient space to play, you could wring some extraordinary pace out of it. That just feels a leap of faith on a wet, busy B road when you’ve audibly made entire neighbourhoods aware of your presence. To acquire this level of performance and still have a warranty (plus a speed limit bong to disengage…) feels outrageous.

The interior is largely stock Mustang, though there’s a neat red RTR starter button and its new gear knob feels fantastic too, perfectly round save for a flat face on which to place your palm for a truly positive shift from second to third in a moment of frenzy. The handbrake lever looks cool, though it operates an electronic parking brake and is fiddly and bordering on a gimmick.

All told, the RTR is wholly driveable with some heat coursing through its tyres; it gets over speed bumps and out of gravel car parks okay, too. It’s not morphed into a liability, though nor will it act the cosy, everyday grand tourer like its donor car seemingly can. You forfeit that particular string of the Mustang’s bow by ordering any RTR, even the demurer Spec 2. But then that’s rather the point.

Tempted? It’s typically two to three weeks between Motorsport and Performance ordering the kit and it being shipped and fitted. If you’re keen to cut the additional waiting time of speccing fresh Mustang, the PH Classifieds offer cars from £45k. Still not enough depreciation to make this Spec 3 car the giveaway it looks back in the States – but you try naming another modern, manual, rear-drive coupe with this kind of clout outside of hypercar money…

SPECIFICATION | 2026 FORD MUSTANG RTR SPEC 3

Engine: 5,038cc supercharged V8
Transmission: 6-speed manual, rear-wheel drive
Power (hp): 750
Torque (Ib ft): 615
0-62mph (secs): 3.5 (est)
Top speed (mph): 180 (est)
MPG (official combined): n/a
CO2 (g/km): n/a
Price: £27,995 (before car), £86,665 (including base 2026 Mustang GT)