Concentrate on the power of the battery, epsecially Cold Cranking Amps, extra toys are all very well but once the battery has died then they are all scrap.

Depends on what you want to jump start, mine is one of these, note it can be found cheaper....www.machinemart.co.uk/shop/product/details/jump-st...0

You won't need such high CCA for a Yaris, but there is nothing worse than a jump pack which doesn't do the job when needed.

Alternatively, spend £40 on some real heavy copper jump leads of a decent length and learn the correct connection routine off by heart.