According to the Which? report of 2006, the Evolva 1-2-3 scored comparatively poorly as it didn't do so well in frontal collisions, only gaining 3 stars (out of max 5 I think), although its side impact protection was given four stars.
Britax produce a rearfacing equivalent (which gets over the whole problem with the performance in the frontal collisions, as rearfacing seats are supposed to be 5 times safer than forward facing ones for the under 4s) which is now available to purchase in the UK. Rearfacing seats for older toddlers are the norm in Scandinavia and are becoming more common in the UK, despite manufacturers/retailers insistence that British consumers are too tight/stupid to shell out/install a rearfacing seat. Check this site out www.rearfacing.co.uk for more information on the whole rear/front facing carseat debate.
If you are interested in trying a rearfacing Britax seat, there is a company in Milton Keynes (www.incarsafetycentre.co.uk/index.html) who sell the rearfacing equivalent of the Evolva 1-2-3 for £250. Its called the Multi Tech now.
In terms of car seat safety, am informed by the experts that a good seat that doesn't fit your car, your child, or is poorly installed, is no good at all. There are places where you can try carseats before you buy, see the website for details.
BTW, am not working on commission, but have been convinced by all the research we read over the summer on this subject.
HTH.