I've got a pulsar Q as well as my r32... around 80kw and 1000kg.. lsd, 1.8L, manual.. goes alright, does burnouts.. about the same as most of the older aussie v6's
The real difference between a 6 and 4cyl is prolly only $5-10 a week.. if you can't afford that, then you probably shouldn't be buying a second car
Think of it this way.. even if you got 6L/100km compared to say 12L/100km.. assuming 500km a week (26,000km a year - way more that you'll probably do), that's 6*5 = 30L x $1.20 = $36 saving a week..
Now take into account rego of $650 a year + 3rd party insurance ($150 for me, more for you) = $800 / 52 = $15 a week to keep the car on the road at the minimum.. add $1000 depreciation/repair costs to the daily in an average year - another $19/wk.. all up $34/wk for your 'cheap' daily to remain on the road