I own a new Tiguan with the 1.4 tsi act engine. I have the se nav model. You'll get lots of comments about the engine being too small etc,but having owned it for 2 months I would make the following comment.
I too was concerned about it being under powered, especially as it was replacing a golf gti performance pack with 230 Bhp and 360nm torque, which i owned for the last 2 years.
Any worries about the engine being under powered have been dispelled. The 1.4 petrol unit really suits it. It obviously hasn't got the torque of the gti, but it does pick up well and you never feel apprehensive about pulling out of junctions. It's a very smooth and progressive power delivery and because of the lighter engine it makes the car suprisingly nimble. I tried the 2 litre diesel and it felt very similar in terms of overall power and torque. The diesel model is @100kg heavier so offsets the difference in torque. I picked this model because I don't tow and don't need 4 wheel drive. I am 6'7 tall and have 3 kids that will soon be taller than me even though they are just in their teens - hence the need for a big car!
I had intended on buying the seat Ateca with this engine, but there are very long delivery times in the uk and the deal I got on the Tiguan was actually better, due to brand loyalty and a great part ex.
The engine is the newer updated unit and has been in the Audi q3 and golf for quite a few years now and there have been very few issues. This engine is the active cylinder tech version or cylinder on demand as described by Audi. This provides a very efficient engine as it goes into 2 cylinder mode when steadily cruising. The 2 cylinder mode is unnoticeable except for the indicator on the dash which tells you it's only running on 2 cylinders. It cruises easily at 70 on the motorway in 2 cylinder mode. I've never been one for pulling into small gaps , so for me it's great as I only really pull into spaces on the motorway that are pretty large, so I don't need the 'whoosh' that the gti gave, but the Tiguan does pull nicely and increase speed really progressively. Because of the progressive nature of the engine it's been returning good mpg. My average after 1000 miles is 45 mpg and that's a mixed set of driving - Short runs on motorway, through town and into city centres. Given that the engine is absolutely new I think that's really good mpg. Incidentally that is actual mpg not just from the ash, the dash actually shows 48.2mpg.
Space wise the car is brill. The kids, very tall ones, love it in the back. They have masses of leg room. I also really like the driving position and being higher up you can really see the edges of the car, so feel comfortable with the size of the car overal as you really know where the edges are.
Overall I'm really pleased.
My summary would be that the 1.4 is a great version of the Tiguan. It's not a towing version and I wouldn't have a 4x4 variant because of the increased weight and mpg offset, but if you want a very nice, refined Tiguan then it's a great model. If you consider the pricing difference it's a couple of thousand pounds cheaper than the diesel 150 Bhp version, which I would say is exactly the same power wise, with the extra weight negating the torque you have in the diesel. Also the 2 litre petrol is actually 180 bhp, so not a massive increase, although it more torquey. In no way am I saying the 180 bhp or 150 bhp engine is or isn't better, but for me the lower mpg and increased co2 was an issue, so I went with the 1.4 engine.
I did think that the engine felt better after the first 300 miles. Almost as if there was a break in engine map in operation until that point. That might just have been me getting used to the car, but since then it's felt more revvy and purposeful.
Have a think about your driving style though before making the purchase. If you like very low, early torque then go diesel. The petrol engine torque kicks in at 1500 rpm, so you have to be in the right gear for it to feel right. My gti made me a very lazy driver as it would pull like a train from 1000 rpm in any gear, so for example I could be in 6th gear at 20mph, bury my foot and it would throw you back like you were taking off. The Tiguan won't do that and you need to pick the right gear, so in the example above you'd need to be in 3rd or at most 4th to get the engine to spin up. I've definitely become a more relaxed driver, just picking my gears appropriately. The Tiguan responds in a great way to that driving style and my wife much prefers it also - she really didn't like it when I used to bury the gti throttle. So for me it's been a great move.
Hope this helps you to make your decision.
I do have a couple of niggles, namely wind noise from the passenger mirror and a dirt spec in the clear coat on the bonnet, but to be honest I got a great deal and these haven't detracted from the car at all.
Regards
Axel