Back in 5th gear at 40 mph should not be bad.
In my Nissan Almera I killed the engine leaving the highway (clutch pedal to the floor, leaving the car in gear) to restart the car by lifting the pedal before the speed got too low or the lights change to green, whatever came first.
Have to mind that power steering and brakes wane quickly without running engine. Always be ready to lift.
As cars get more and more complex with ECU, EGR, stability control etc. this technique will at some time become impractical, if not harmful. So be warned.
Actually, if the engine and gearbox allow it getting towed while in 5th gear may be an option to retain power steering and brakes, you really have to stand on the brake otherwise to get a reasonable effect.
But your Fiat is unlikely to ever need towing of course. This is meant for the driver you tow, to help him to not hit your nice car when you need to brake
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2011 Honda Insight + HID, LEDs, tiny PV panel, extra brake pad return springs, neutral wheel alignment, 44/42 PSI (air), PHEV light (inop), tightened wheel nut.
lifetime FE over 0.2 Gigameter or 0.13 Megamile.
For confirmation go to people just like you.
For education go to people unlike yourself.