My suggestion is;
Drive via SH 2 to Te Puke (drive by kiwi fruit farms) and take SH33 then SH 30 to Rotorua. (Approx. 60 mins)
Te Puia (
Kuirau Park (free) & city walk.
Rotorua Museum and Government Gardens...not just a museum but an experience.
Ohinemutu Maori Village (possible small fee)
Agrodome Sheep Show & Farm Tour (lots of adrenaline activities here such as bungy, zorb,schweeb, and others)
Drive through Ngongotaha Village and take SH 36 Tauranga Direct Road.
Do a little detour before turning into Tauranga Direct Road and drive through Hamurana Just past golf course and before bridge, turn left and do the 20 minute Hamurana Springs walk.
Return to SH 36 Tauranga Direct Road .
Reaching Tauranga, take Mt Maunganui Road.
There are lots of other activities & things to see but this will fill in your day.