I am used to driving big Diesel cars, but when i took my mk4 st line ecoboost for a test drive, i commented on how the engine sounded (loud and like it was struggling). The salesman said that was normal. Is it normal ? I've read a review that says its best to drive the car between 3,500 - 5,500 revs, Is this correct ?

Other than this enquiry, I absolutely LOVE this car !!!

Shouldn't sound like it is struggling, only time you would really need to drive the car around them revs is if you need the power, e.g overtaking, cars are louder when cold once warmed up a bit they tend to be okay

Mine sounds like it's 'labouring' when cold unless I keep in a low gear (I put it down to having three cylinders rather than my old MK1, with four). It could be that my particular cars engine is running low on revs (?), but once the engine is warm I hardly notice the labouring...although I have to keep to lower gears compared to my old 2 litre engine, which I guess is correct (?). As for the rpm, mine sits between 1,500-2,000 maximum. I have only seen it get to 3,000 rpm when I accidentally put it in 2nd gear at 25 mph, in error.