On this page of the trophy guide to Mafia Definitive Edition, you will find a detailed description of unlocking the That Motor Can Move achievement. You get this trophy for going 50 miles per hour in Bolt Ace. Below we present the perfect place for getting this trophy.
The best mission to get this trophy is Fairplay. It takes place at night so traffic is much smaller. Also, the initial part of it gives you the freedom of choosing a vehicle. After talking to Ralph, you can use the garage for the first time in the main storyline. Choose the Bolt Ace vehicle, which is one of the slowest cars in the game.
Do not follow the mission objective leading to the racetrack. Instead, choose the route shown in the image above. You need to turn east and head towards the West River Tunnel.
Drive on the tram tracks in the middle and avoid slowing down and colliding with trams and vehicles.
Turn slightly to the right towards the tunnel. This is road leads down, allowing the Bolt Ace to ride faster than its maximum speed. That should be enough to get the trophy.