So I've been looking into what awards the Z cars (40+ years old) an MOT exemption and for most people it's fairly straight forward - as long as it's not "significantly" modified and 40+ years old then you're good to go. The grey area comes to modifications, primarily (for me at least) engine changes. The old rules didn't penalise engine changes nearly as much as suspension, brakes, etc, but that's now gone and it's been replaced with this document which is fairly vague: https://assets.publishing.service.g...ical-interest-substantial-change-guidance.pdf And here: https://www.gov.uk/government/publi...toric-classic-vehicles-mot-exemption-criteria Now I've always assumed that because the engine in my car has been swapped (from a 70's 2.4L to a 90's 2.5L) then I'd fall under the "not exempt" category. Except apparently that's not always the case. A few friends that own various classics (Land Rovers, Mini's, Porsche, Lotus etc) have all had pretty lenient exemptions. The following points hold true: changes were made to running gear in order to improve efficiency, safety or environmental performance the changes were made to preserve a vehicle where original parts are no longer available Alternative cubic capacities of the same basic engine and alternative original equipment engines are not considered to be a substantial change. For example, for us I imagine that means going from an L24 to an L28, or rebuilding your L24 (or L28) to 3.0L etc. Now obviously there's a lot of grey lines and therefore they suggest to contact an expert clarification. I contacted the legislation experts over at FBHVC but they were unable to give specific advice and suggested I looked for an in-house expert here at ZClub. Does the club have a resident expert that people could talk to with regards to VHI status? I figure it'd be ideal to get something sorted out as this will be a pretty common question for anyone that wants to get a VHI but have modified their cars in whatever way.