Valve-free motoring

QI fancy a twostroke car. I’m not bothered what sort… I just love the sound. I’ll buy something in mainland Europe. It’ll need to pass an MOT to be registered – but will the emissions be a problem? How do I know how much oil to put in? Zac Jones, Southampton

AA two-stroke car is simply tested to make sure that it doesn’t emit excess smoke. As long as you’re using the correct ratio of oil and it’s had a short run to purge excess from the crankcase and exhaust, this won’t be a problem. Add the oil in the ratio stated by the manufacturer. It’s self-mixing, so it’s enough to pour the required quantity into the tank then pour the petrol in on top.