Sounds like the car went into limp mode. This is when the computer locks the car in 2nd gear to prevent further damage from whatever fault it sensed. Sometimes it can just be a bug in the system, and resetting it can fix it. However, smoke from the engine bay is cause for concern. I would just keep a close eye on it. If you notice anything out of the ordinary or the check engine light comes on, take it to a mechanic.

It sounds like it had a throttle position sensor failure. I haven't heard of it in Nissans but they are a major problem in Fords and Volvos from the previous decade. My partner's wife had the same sort of thing happen twice in her 2000 Explorer... replacing the TPS stopped it.

There must be problem in your accelerator or as the mechanic said the CPU must have gone out of order. CPU i.e the central processing unit controls most of the vital processes of your automobile.

take your car to car wash , that's all !

go with cosmo

I have a 2007 nissan Altima that I get serviced regularly. Yesterday on the highway at 75 it jolted out of cruise control and then wouldn't go below like 4 thousand rpm. I pulled over, there was just a bit of smoke coming out of the engine compartment but nothing crazy. A car repair guy checked it out, had me reset my cars CPU and I got back on the highway to which the car drove fine like nothing happened. Does anyone know what the hell happened?