Looking at the Wiki page, 2nd generation Smarts got a 5 speed manual option. I've no idea but perhaps the gearbox or even whole rear clip from a later car would dal with the semi-auto issue. But it's starting to look like a project then.
From Wiki
Transmissions
The first and second-generation Fortwo models employ an automated manual transmission, designed and manufactured by Getrag, where the clutch is computer-controlled via electrohydraulics, eliminating the need for a clutch pedal. The first generation used a six-speed version, and the second generation uses a five-speed version, model 5AMT130. Input from floor-mounted shifter or optional steering-wheel-mounted paddles controls a servo-operated clutch and an automated manual gearbox. The vehicle may be driven in automatic mode (early models had the option of fully automatic mode or standard "soft-tip" which was manual mode indicated by no button on the gearshift) or in semi-automatic (half-automatic) mode via paddle-shifters, where the operator controls the shift points but cannot feather or adjust the speed of the clutch.
From 2009, revised transmission software enabled smoother and faster gear changes. The software, available via an ECU upgrade, was also made available for 2008 second generation cars, with a new battery as required.[21][22]
Third-generation models receive a five-speed manual transmission or dual-clutch automatic transmission.
From Wiki
Transmissions
The first and second-generation Fortwo models employ an automated manual transmission, designed and manufactured by Getrag, where the clutch is computer-controlled via electrohydraulics, eliminating the need for a clutch pedal. The first generation used a six-speed version, and the second generation uses a five-speed version, model 5AMT130. Input from floor-mounted shifter or optional steering-wheel-mounted paddles controls a servo-operated clutch and an automated manual gearbox. The vehicle may be driven in automatic mode (early models had the option of fully automatic mode or standard "soft-tip" which was manual mode indicated by no button on the gearshift) or in semi-automatic (half-automatic) mode via paddle-shifters, where the operator controls the shift points but cannot feather or adjust the speed of the clutch.
From 2009, revised transmission software enabled smoother and faster gear changes. The software, available via an ECU upgrade, was also made available for 2008 second generation cars, with a new battery as required.[21][22]
Third-generation models receive a five-speed manual transmission or dual-clutch automatic transmission.
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