How much are the cars you're looking at/ballparking, vs everything else?
If you're talking a relatively small amount of money vs your net worth/income, your net worth becomes your own insurance - you just buy on credit and pay it off in a couple of months from income.
If you're financially tight it's different. It also depends on the cars - 180k isn't all that much, and neither is 215k, if you have good solid generally maintained cars (I'm presuming you're talking kms here not miles). And of course it depends on how much you drive, etc, etc.
It is very 'hand wavey'. Have enough in cash that you feel comfortable. Remember there are good short term savings accounts if you can be bothered (EQ Bank are doing a 3 month GIC, Simplii and Tangerine have temporary bonuses, all at greater than 3%; and EQ Bank's general account is at 2.3%). Invest the rest. Or just have it as part of your general emergency fund, assuming you have enough slack.