Carma reads Singapore's used-car listings around the clock and gives each car a Carma score out of 100 against similar cars: depreciation (half the score), mileage per year, number of owners and COE left. It flags price cuts and how long a car has been on the market, takes COE renewals out of asking prices so cars compare like for like, and has price guides for over 500 models. Free, no sign-up needed.