The M235i might be gone, but the replacement has even more performance. We took a short, topless, drive, to see if the M240i stacks up as a cut-price M2 alternative.

Full disclosure. The M240i does not have a 4.0-litre engine. BMW nomenclature has paid little attention to engine capacity for years, so don’t be fooled. No, under the bonnet is a 3.0-litre straight-six TwinPower turbo engine, that has gained more horsepower and torque. Peak power has increased to 335hp – a rise of 14hp – whilst twist is up to 369lb-ft. That last figure is significant for two reasons: it’s the same torque as found in the E39 M5 but, more importantly, it’s the exact same amount as the M2 Coupé.

Performance is improved over the M235i, with 0-62mph taking just 4.7 seconds in the M240i when fitted with the optional eight-speed Sport Automatic gearbox. The six-speed manual car needs 4.9 seconds to do the same sprint, with both topping out at an electronically limited 155mph top speed. We didn’t experience the three pedal car, so can’t comment on how it compares, but the automatic ‘box is supremely efficient and effective at banging through the ratios. Eight gears are probably overkill, especially with so much torque on offer, but they contribute to respectable sounding CO2 and mpg figures.

The automatic transmission also suits the slightly more laid-back, cruiser, image of the Convertible version. Going topless in the M240i incurs a penalty of 145kg in additional weight compared to the regular M240i Coupé. That’s the equivalent of two average-sized passengers, which is substantial cargo, even if BMW maintains the performance difference between hard-top and Cabriolet is technically minimal. Combined with the price premium, it means you’ve really got to want a soft-top.

The M240i also serves as a reminder of just how good a rear-wheel drive car can be. It might seem a little clichéd, but you honestly can feel the car pivoting around your hips, along with the sensation of being pushed along by the rear axle. The compact wheelbase of the M240i amplifies its agility, and the whole car seems designed to fit twisty British backroads. The steering isn’t hugely communicative in itself, but the overall feedback you get from the car allows you to push on with confidence. The ride is also remarkably well controlled for a sporty car and makes for an all-round usable package. Traction, even on greasy autumnal roads, was strong and the M240i is happy to launch itself down the road with minimal fuss.

Externally nothing has changed from the M235i, which isn’t necessarily a bad thing. This is still a well-proportioned compact cabriolet, and one that manages to look quite subtle in Black Sapphire metallic paint. Were it not for the blue brake calipers and twin exhaust pipes, you could quite easily mistake this for a lukewarm 218d M Sport. Our test car featured the no-cost option Coral Red Dakota leather trim inside. It’s as red as it appears in the photos, and not like it seems on the BMW configurator website. We liked it, but just be warned!

In fact our only major criticisms of the M240i come in the form of the interior. Although it may be acceptable in a base-spec 218d, at this kind of price things like the cheap 12v socket cover, and awkward-looking union between door card and dashboard, seem a little of out place. These are minor points but, at over £40,000, the M240i Convertible is hardly a bargain-basement machine. The iDrive unit, accessed through a rotary controller and not a touchscreen, can be frustratingly unintuitive at times. More time spent with it would make this less of an issue, however.

Overall, the M240i is a deeply impressive car. It’s obviously not an M2 – especially not in Convertible form – but it still offers up a lot of the excitement and ability of the current M-car king. The M240i Coupé – or even the M140i hatchback – would be closer to our ideal M machine but, whichever flavour you pick, it comes with the benefit of the glorious TwinPower straight-six turbo engine. That power plant is the star of the show here, and proves that turbocharging doesn’t have to mean a loss of character, especially when you’re playing with more than four cylinders.

Although it isn’t an M2 – BMW has clearly stage-managed enough of a difference between the two products – it is still a convincing rear-wheel drive  alternative to super hot hatches like the VW Golf R or Mercedes-AMG A45. There’s also the saving of some £10,000 to consider over the M2, if you can live with having the second best 2 Series M-car. Think of it as like finishing second to Usain Bolt – still a deeply impressive place to be.

ESM Rating: 7.5/10

Specs – BMW M240i Convertible
Engine: 3.0-litre inline six-cylinder turbocharged petrol
Gearbox: Eight-speed automatic, rear-wheel drive
Power: 335hp [340PS]
Torque: 236lb-ft [500Nm]
0-62mph: 4.7 seconds
Top Speed: 155mph
Economy: 38.2mpg – official combined
C02: 169g/km
Basic Price: £38,535
As Tested: £44,525 [£1,400 Sport Auto gearbox, £550 Black Sapphire metallic paint, £1,795 Innovation package, £520 Driver Comfort package, £660 Harmon Kardon speakers, £440 Visibility package, £295 Heated Seats, £330 Reversing Assist Camera]