A South Australian man will be finding a new way home after he was allegedly caught speeding with alcohol in his system.

The 23-year-old probationary driver was nabbed near Horsham travelling at an alleged speed of 145 km/h in a 100 km/h zone on the Western Highway about 4 pm on Saturday afternoon.

Police intercepted the vehicle, with the driver testing positive to a preliminary breath test.

He then went back to the station and returned an alleged blood alcohol concentration of 0.027.

The man is expected to be charged on summons with speeding, drink driving and driving while suspended.