A good example of this is the Audi Q3. Thanks to the company’s confusing naming strategy, it can be very difficult to notice any great difference between the 150 TFSI and 204 TFSI quattro options. Both use turbocharged four-cylinder petrol engines and neither is seen as a performance ‘flagship’, so they sit in the middle of the Q3 range. Models with these powertrains also look the same, and for the most part even drive pretty much identically. 

However, while you won’t always spot the difference in power (roughly 50bhp), you will notice the variation in fuel economy. Choosing the more powerful 204 TFSI unit turns a decent 43mpg into 34mpg, which is pretty terrible for a car the size of a Q3 and will make a noticeable difference to your fuel bills. This isn’t just the case for Audis, of course, but all petrol-powered cars that offer various powertrains in a single model. 

While you’re at the sales desk, there’s also a chance that for the sake of ease or availability, your sales rep will offer you a slightly different variant to the one you’ve just driven. This is not necessarily a problem, but before you sign on any dotted line, take an extra moment to consider exactly what engine is under the bonnet. Failure to do so could see you landed with a gas guzzler that will cost you big-time in the long run.