A Cromwell man who caused an underage driver to drive his car after they had been drinking has been sent to prison for more than two years.

Gareth Allen Evan Voight, 40, was charged with two counts of reckless use of a motor vehicle causing injury, and one count of supplying alcohol to a person under 18 in Alexandra on October 21.

Although Voight was not driving the vehicle, police had previously said they could lay the reckless driving charge if a person had caused a vehicle to be driven.

Counsel for Voight, Kieran Tohill, said in the Alexandra District Court yesterday Voight's behaviour had been "outrageous" and "bad decisions mixed with alcohol" had caused the crash.

The car driven by the teenager crashed on Little Valley Rd, east of Alexandra.

Judge Kevin Phillips said Voight and the 15-year-old had been drinking together in Cromwell and Voight asked the boy to drive him to Clyde, where they kept drinking.

They then went to the Alexandra boat ramp and picked up two youths aged 16 and 18. The 18-year-old bought more alcohol from an outlet.

The 15-year-old then drove "at speed" around Alexandra and across a bridge to Little Valley Rd, where he lost control of the car. It smashed into a large rock, mounted the adjacent bank and came to rest on its side in a ditch. The 15-year-old was estimated to be driving at 88kmh at the time of the crash, and he had a breath-alcohol limit of 678mcg.

There were no seats or restraints in the back of the unregistered, unwarranted vehicle. The 16-year-old received a broken nose and a bruised leg, and the 18-year-old received a concussion, bruising and lacerations. Voight received a fractured sternum and eye socket, and a bruised spine.

Judge Phillip said Voight's recklessness was at "the high end of the scale" and he had an "alarming and appalling" criminal history relating to motor vehicles.

He sentenced him to two years and one month's imprisonment, and disqualified him from driving for two years.