Which Astra GTC should you order? 04 January 2012 by Parkers Team We take you through how to order an Astra GTC Which engine do you want, and what can you afford? Is it worth going for top spec SRi trim or will Sport do? A few months ago we tested the most impressive Astra in the range, the three-door GTC. We suspect it would make an excellent company car, but as with most Vauxhalls these days there are myriad trim and engine options to decide between. So which should you go for? We’ve gone through the differences so you don’t have to. Engine: There are currently five engine offerings for the GTC. There’s a trio of petrol engines, a 1.4-litre producing either 120bhp or 158bhp and a 1.6-litre producing 178bhp. Emissions are 140g/km for the 1.4 and 168g/km for the 1.6. The trio of diesel engines stack up as a 1.7-litre with 108bhp or 128bhp and a 2.0-litre with 163bhp, with emissions of 119g/km and 127g/km of CO2 respectively. So which one to pick? Well, there’s always the performance vs cost consideration. The petrol units can be discounted immediately thanks to their higher CO2 emissions than the diesels, meaning company car tax will be higher. For instance, the low-power petrol engine emitting 140g/km will incur an 18% company car tax liability, while the 1.7-litre diesel emits 119g/km, placing it in the 13% BIK band. A difference of 5% is fairly substantial. So it’s clear from a company car driver’s perspective that a diesel is the way to go. However, which diesel to pick? The performance stats are quite different. The 1.7-litre diesel will take either 10 or 11 seconds to get to sixty depending on power output, with top speeds of 113mph for the slower or the two and 122mph for the faster one. The higher power diesel engine sits in the same BIK band as the slowest petrol engine, yet pips it by almost two seconds to sixty – 8.4 seconds instead of 10.2 - and has a top speed of 131mph as opposed to 119mph. As you can see there’s a marked difference between the 1.7-litre engines and the 2.0-litre. Gearbox: There’s only one gearbox option – a six speed manual. Trim level: There are two trim options. You can go for Sport, which is the base spec and nets you equipment such as 18-inch alloys, cruise control, daytime running lights, air con, USB and iPod control and a CD/MP3 player. Alternatively, for £1270 (give or take a fiver) you can upgrade to SRi spec. This means you get tinted glass, an electronic parking brake with hill start assist, a fancy alarm system, sports seats, some different alloys, the ‘sight and light’ pack – which includes auto wipers, auto headlights, electro-chromatic rear view mirror and high bear assist - and front fog lights. Costs: So let’s break the differences down into cold, hard company car tax costs. A GTC with the 1.7-litre low-power engine in Sport trim will have a P11d of £20,005 so will cost £87 per month on the 40% pay scale. To upgrade to SRi trim will cost an extra £5 per month. A GTC with the 1.7-litre high-power engine in Sport trim will have a P11d of £20,605 so will cost £89. To upgrade to SRi trim will cost an extra £5 per month. A GTC with the 2.0-litre low-power engine in Sport trim will have a P11d of £21,110 so will cost £126.66. To upgrade to SRi trim will cost an extra £8 per month. You can see from these calculations that the 2.0-litre is far more expensive per month; in fact, it is around £38 per month more, which adds up to £1355 over the course of a three year lease in company car tax alone. Compare that to the difference between the two 1.7-litre engines, which at £2 per month equates to £72 over the same three year period, and there’s only one sensible way to go. For that touch of extra performance without driving your bills up too high, we’d suggest you go for the 1.7 with 128bhp. Whether or not you decide to go for the SRi specification over the standard Sport spec is a matter of some debate. Our feeling is that you get quite a lot of extra equipment with the higher trim level, and features such as hill hold assist and auto wipers are extremely useful. For the small extra monthly outlay, we'd choose SRi. Parkers' pick: Vauxhall Astra GTC SRi 1.7 (128bhp) Cost per month in company car tax on 40% pay scale: £94 Tweet Related articles on Parkers Company car tax: planning ahead Company car tax changes in 2014/15 Saloon cars that cost less than £75 in BIK Calculating company car tax in 2013/14 What's so special about 130g/km?